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For each in 1st array count less than or equal to it in 2nd array

Last Updated : 28 Jun, 2025
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Given two unsorted arrays a[] and b[]. Both arrays may contain duplicate elements. For each element in a[], find the count of elements in b[] are less than or equal to that element.

Examples:

Input: a[] = [1, 2, 3, 4, 7, 9], b[] = [0, 1, 2, 1, 1, 4]
Output: [4, 5, 5, 6, 6, 6]
Explanation:
For a[0] = 1, there are 4 elements in b (0, 1, 1, 1) that are ≤ 1.
For a[1] = 2, there are 5 elements in b (0, 1, 1, 1, 2) that are ≤ 2.
For a[2] = 3, there are 5 elements in b that are ≤ 3.
Similarly, for a[3] = 4, there are 6 elements in b that are ≤ 4, and for a[4] = 7 and a[5] = 9, there are also 6 elements in b that are ≤ 7 and ≤ 9, respectively.

Input: a[] = [4, 8, 7, 5, 1], b[] = [4, 48, 3, 0, 1, 1, 5]
Output: [5, 6, 6, 6, 3]
Explanation:
For a[0] = 4, there are 5 elements in b (4, 3, 0, 1, 1) that are ≤ 4.
For a[1] = 8 and a[2] = 7, there are 6 elements in b that are ≤ 8 and ≤ 7.
For a[3] = 5, there are 6 elements in b that are ≤ 5.
For a[4] = 1, there are 3 elements in b (0, 1, 1) that are ≤ 1.

Table of Content

[Naive Approach] Using Nested Loops - O(n * m) Time and O(n) Space

The idea is to use two loops, the outer loop iterates through each element in array a[], and for every element in a[], the inner loop traverses array b[] to count how many elements in b[] are less than or equal to the current element from a[].

C++ 
#include <iostream>
#include <vector>
using namespace std;

vector<int> countLessEq(vector<int>& a, vector<int>& b) {
    
    int n = a.size(), m = b.size();

    // to store the result
    vector<int> res(n);

    // outer loop for each element of a[]
    for (int i = 0; i < n; i++) {
        int count = 0;

        // inner loop for each element of b[]
        for (int j = 0; j < m; j++)
            if (b[j] <= a[i])
                count++;

        res[i] = count;
    }

    return res;
}

int main() {
    vector<int> a = {1, 2, 3, 4, 7, 9};
    vector<int> b = {0, 1, 2, 1, 1, 4};
    vector<int> result = countLessEq(a, b);
    for (int i : result) {
        cout << i << " ";
    }
    return 0;
}
Java 
import java.util.*;

class GfG {

    // to store the result
    public static ArrayList<Integer> countLessEq(int[] a, int[] b) {
        int n = a.length, m = b.length;

        // to store the result
        ArrayList<Integer> res = new ArrayList<>();

        // outer loop for each element of a[]
        for (int i = 0; i < n; i++) {
            int count = 0;

            // inner loop for each element of b[]
            for (int j = 0; j < m; j++)
                if (b[j] <= a[i])
                    count++;

            res.add(count);
        }

        return res;
    }

    public static void main(String[] args) {
        int[] a = {1, 2, 3, 4, 7, 9};
        int[] b = {0, 1, 2, 1, 1, 4};
        ArrayList<Integer> result = countLessEq(a, b);
        for (int i : result) {
            System.out.print(i + " ");
        }
    }
}
Python 
def countLessEq(a, b):
    n = len(a)
    m = len(b)

    # to store the result
    res = [0] * n

    # outer loop for each element of a[]
    for i in range(n):
        count = 0

        # inner loop for each element of b[]
        for j in range(m):
            if b[j] <= a[i]:
                count += 1

        res[i] = count

    return res

if __name__ == "__main__":
    a = [1, 2, 3, 4, 7, 9]
    b = [0, 1, 2, 1, 1, 4]
    result = countLessEq(a, b)
    for i in result:
        print(i, end=" ")
C# 
using System;
using System.Collections.Generic;

class GfG {

    public static List<int> countLessEq(int[] a, int[] b) {
        int n = a.Length, m = b.Length;

        // to store the result
        List<int> res = new List<int>();

        // outer loop for each element of a[]
        for (int i = 0; i < n; i++) {
            int count = 0;

            // inner loop for each element of b[]
            for (int j = 0; j < m; j++)
                if (b[j] <= a[i])
                    count++;

            res.Add(count);
        }

        return res;
    }

    public static void Main(string[] args) {
        int[] a = {1, 2, 3, 4, 7, 9};
        int[] b = {0, 1, 2, 1, 1, 4};
        List<int> result = countLessEq(a, b);
        foreach (int i in result) {
            Console.Write(i + " ");
        }
    }
}
JavaScript 
function countLessEq(a, b) {
    let n = a.length, m = b.length;

    // to store the result
    let res = new Array(n);

    // outer loop for each element of a[]
    for (let i = 0; i < n; i++) {
        let count = 0;

        // inner loop for each element of b[]
        for (let j = 0; j < m; j++)
            if (b[j] <= a[i])
                count++;

        res[i] = count;
    }

    return res;
}

let a = [1, 2, 3, 4, 7, 9];
let b = [0, 1, 2, 1, 1, 4];
let result = countLessEq(a, b);
console.log(result.join(" "));

Output
4 5 5 6 6 6

[Better Approach - 1] Using Sorting - O((n + m) * log m) Time and O(n) Space

The idea is to sort the elements of array b[], then perform a modified binary search on array b[]. For each element x of array a[], find the last index of the largest element smaller than or equal to x in sorted array b[]. The index of the largest element will give the count of elements.

C++ 
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

// to perform the binary search
int binarySearch(vector<int> &arr, int x) {
    int low = 0, high = arr.size() - 1;

    while (low <= high) {
        int mid = low + (high - low) / 2;
        if (arr[mid] <= x)
            low = mid + 1;
        else
            high = mid - 1;
    }
    return low;
}

vector<int> countLessEq(vector<int>& a, vector<int>& b) {
    int n = a.size(), m = b.size();

    // to store the result
    vector<int> res(n);

    // sort the array b[]
    sort(b.begin(), b.end());

    // outer loop for each element of a[]
    for (int i = 0; i < n; i++) {
        res[i] = binarySearch(b, a[i]);
    }

    return res;
}

int main() {
    vector<int> a = {1, 2, 3, 4, 7, 9};
    vector<int> b = {0, 1, 2, 1, 1, 4};
    vector<int> result = countLessEq(a, b);
    for (int i : result) {
        cout << i << " ";
    }
    return 0;
}
Java 
import java.util.*;

class GfG {

    // to perform the binary search
    static int binarySearch(int[] arr, int x) {
        int low = 0, high = arr.length - 1;

        while (low <= high) {
            int mid = low + (high - low) / 2;
            if (arr[mid] <= x)
                low = mid + 1;
            else
                high = mid - 1;
        }
        return low;
    }

    static ArrayList<Integer> countLessEq(int[] a, int[] b) {
        int n = a.length, m = b.length;

        // to store the result
        ArrayList<Integer> res = new ArrayList<>();

        // sort the array b[]
        Arrays.sort(b);

        // outer loop for each element of a[]
        for (int i = 0; i < n; i++) {
            res.add(binarySearch(b, a[i]));
        }

        return res;
    }

    public static void main(String[] args) {
        int[] a = {1, 2, 3, 4, 7, 9};
        int[] b = {0, 1, 2, 1, 1, 4};
        ArrayList<Integer> result = countLessEq(a, b);
        for (int i : result) {
            System.out.print(i + " ");
        }
    }
}
Python 
# to perform the binary search
def binarySearch(arr, x):
    low = 0
    high = len(arr) - 1

    while low <= high:
        mid = low + (high - low) // 2
        if arr[mid] <= x:
            low = mid + 1
        else:
            high = mid - 1
    return low

# to store the result
def countEleLessThanOrEqual(a, b):
    n = len(a)
    m = len(b)

    # to store the result
    res = [0] * n

    # sort the array b[]
    b.sort()

    # outer loop for each element of a[]
    for i in range(n):
        res[i] = binarySearch(b, a[i])
    return res

if __name__ == "__main__":
    a = [1, 2, 3, 4, 7, 9]
    b = [0, 1, 2, 1, 1, 4]
    result = countEleLessThanOrEqual(a, b)
    for i in result:
        print(i, end=" ")
C# 
using System;
using System.Collections.Generic;

class GfG {

    // to perform the binary search
    static int binarySearch(int[] arr, int x) {
        int low = 0, high = arr.Length - 1;

        while (low <= high) {
            int mid = low + (high - low) / 2;
            if (arr[mid] <= x)
                low = mid + 1;
            else
                high = mid - 1;
        }
        return low;
    }

    // to store the result
    static List<int> countLessEq(int[] a, int[] b) {
        int n = a.Length, m = b.Length;

        // to store the result
        List<int> res = new List<int>();

        // sort the array b[]
        Array.Sort(b);

        // outer loop for each element of a[]
        for (int i = 0; i < n; i++) {
            res.Add(binarySearch(b, a[i]));
        }

        return res;
    }

    public static void Main(string[] args) {
        int[] a = {1, 2, 3, 4, 7, 9};
        int[] b = {0, 1, 2, 1, 1, 4};
        List<int> result = countLessEq(a, b);
        foreach (int i in result) {
            Console.Write(i + " ");
        }
    }
}
JavaScript 
// to perform the binary search
function binarySearch(arr, x) {
    let low = 0, high = arr.length - 1;

    while (low <= high) {
        let mid = low + Math.floor((high - low) / 2);
        if (arr[mid] <= x)
            low = mid + 1;
        else
            high = mid - 1;
    }
    return low;
}

function countLessEq(a, b) {
    let n = a.length, m = b.length;

    // to store the result
    let res = new Array(n);

    // sort the array b[]
    b.sort((x, y) => x - y);

    // outer loop for each element of a[]
    for (let i = 0; i < n; i++) {
        res[i] = binarySearch(b, a[i]);
    }

    return res;
}

let a = [1, 2, 3, 4, 7, 9];
let b = [0, 1, 2, 1, 1, 4];
let result = countLessEq(a, b);
console.log(result.join(" "));

Output
4 5 5 6 6 6

[Better Approach - 2] Using Inbuilt Function - O((n + m) * log m) Time and O(n) Space

Instead of implementing the binary search in the above approach, we can use inbuilt function upper bound in C++ (and bisect_right in Python) that returns the first index ind in the array where the value arr[ind] > target.

C++ 
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

vector<int> countLessEq(vector<int>& a, vector<int>& b) {
    int n = a.size(), m = b.size();

    // to store the result
    vector<int> res(n);

    // sort the array b[]
    sort(b.begin(), b.end());

    // outer loop for each element of a[]
    for (int i = 0; i < n; i++) {
        res[i] = upper_bound(b.begin(), 
        b.end(), a[i]) - b.begin();
    }

    return res;
}

int main() {
    vector<int> a = {1, 2, 3, 4, 7, 9};
    vector<int> b = {0, 1, 2, 1, 1, 4};
    vector<int> result = countLessEq(a, b);
    for (int i : result) {
        cout << i << " ";
    }
    return 0;
}
Java 
import java.util.*;

class GfG {

    // to perform upper_bound functionality
    static int upperBound(int[] arr, int x) {
        int low = 0, high = arr.length;
        while (low < high) {
            int mid = low + (high - low) / 2;
            if (arr[mid] <= x)
                low = mid + 1;
            else
                high = mid;
        }
        return low;
    }

    // to store the result
    public static ArrayList<Integer> countLessEq(int[] a, int[] b) {
        int n = a.length, m = b.length;

        // sort the array b[]
        Arrays.sort(b);

        // outer loop for each element of a[]
        ArrayList<Integer> res = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            res.add(upperBound(b, a[i]));
        }

        return res;
    }

    public static void main(String[] args) {
        int[] a = {1, 2, 3, 4, 7, 9};
        int[] b = {0, 1, 2, 1, 1, 4};
        ArrayList<Integer> result =  countLessEq(a, b);
        for (int i : result) {
            System.out.print(i + " ");
        }
    }
}
Python 
def countLessEq(a, b):
    n = len(a)
    m = len(b)

    # sort the array b[]
    b.sort()

    # to store the result
    res = [0] * n

    # outer loop for each element of a[]
    for i in range(n):
        # bisect_right is equivalent to upper_bound
        import bisect
        res[i] = bisect.bisect_right(b, a[i])
    return res

if __name__ == "__main__":
    a = [1, 2, 3, 4, 7, 9]
    b = [0, 1, 2, 1, 1, 4]
    result = countLessEq(a, b)
    for i in result:
        print(i, end=" ")
C# 
using System;
using System.Collections.Generic;

class GfG {

    // to perform upper_bound functionality
    static int UpperBound(int[] arr, int x) {
        int low = 0, high = arr.Length;
        while (low < high) {
            int mid = low + (high - low) / 2;
            if (arr[mid] <= x)
                low = mid + 1;
            else
                high = mid;
        }
        return low;
    }

    
    public static List<int> countLessEq(int[] a, int[] b) {
        int n = a.Length, m = b.Length;

        // sort the array b[]
        Array.Sort(b);

        // outer loop for each element of a[]
        List<int> res = new List<int>();
        for (int i = 0; i < n; i++) {
            res.Add(UpperBound(b, a[i]));
        }

        return res;
    }

    public static void Main(string[] args) {
        int[] a = {1, 2, 3, 4, 7, 9};
        int[] b = {0, 1, 2, 1, 1, 4};
        List<int> result = countLessEq(a, b);
        foreach (int i in result) {
            Console.Write(i + " ");
        }
    }
}
JavaScript 
// to perform upper_bound functionality
function upperBound(arr, x) {
    let low = 0, high = arr.length;
    while (low < high) {
        let mid = low + Math.floor((high - low) / 2);
        if (arr[mid] <= x)
            low = mid + 1;
        else
            high = mid;
    }
    return low;
}

function countLessEq(a, b) {
    let n = a.length, m = b.length;

    // sort the array b[]
    b.sort((x, y) => x - y);

    // outer loop for each element of a[]
    let res = new Array(n);
    for (let i = 0; i < n; i++) {
        res[i] = upperBound(b, a[i]);
    }

    return res;
}

let a = [1, 2, 3, 4, 7, 9];
let b = [0, 1, 2, 1, 1, 4];
let result = countLessEq(a, b);
console.log(result.join(" "));

Output
4 5 5 6 6 6

[Better Approach - 3] Using Sorting and Two Pointers - O(n*logn + m*logm) Time and O(n) Space

The core idea is to first pair each element of a[] with its original index and sort the array based on values. Similarly, b[] is sorted to enable efficient traversal. Using a two-pointer approach, we iterate through b[] just once, incrementing the pointer whenever the current element in b[] is less than or equal to the current element in a[]. This gives us the count of such elements efficiently. Finally, the count is stored at the original index of the corresponding element in a[], ensuring the result maintains the initial ordering of a[].

C++ 
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

vector<int> countLessEq(vector<int>& a, vector<int>& b) {
    int n = a.size(), m = b.size();
    
    // To store the final result
    vector<int> res(n);  
    
    // Pair of (value, original_index) for sorting
    vector<pair<int, int>> sortedA;  

    // Attach original indices to values for array a[]
    for (int i = 0; i < n; i++) {
        sortedA.push_back({a[i], i});
    }

    // Sort a[] (with index tracking) and b[]
    sort(sortedA.begin(), sortedA.end());
    sort(b.begin(), b.end());

    int ind = 0;  

    // For each element in sorted a[], 
    // count elements in b[] less than or equal to it
    for (int i = 0; i < n; i++) {
        
        // Move pointer while current b element is <= current a element
        while (ind < m && b[ind] <= sortedA[i].first) {
            ind++;
        }

        // Store result at the original index of current a element
        res[sortedA[i].second] = ind;
    }

    return res;
}

int main() {
    vector<int> a = {1, 2, 3, 4, 7, 9};
    vector<int> b = {0, 1, 2, 1, 1, 4};

    vector<int> result = countLessEq(a, b);

    for (int count : result) {
        cout << count << " ";
    }

    return 0;
}
Java 
import java.util.*;

class GfG {

    public static ArrayList<Integer> countLessEq(int[] a, int[] b) {
        int n = a.length, m = b.length;

        // To store the final result, initialized to 0s
        ArrayList<Integer> res = new ArrayList<>(Collections.nCopies(n, 0));

        // Create a list of pairs (value, original index) from a[]
        List<int[]> sortedA = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            sortedA.add(new int[]{a[i], i});
        }

        // Sort sortedA by value, and sort b[]
        sortedA.sort(Comparator.comparingInt(p -> p[0]));
        Arrays.sort(b);

        int ind = 0;

        // Traverse each element in sorted a[]
        for (int[] pair : sortedA) {
            int val = pair[0];
            int origIndex = pair[1];

            // Count how many elements in b[] are <= current a element
            while (ind < m && b[ind] <= val) {
                ind++;
            }

            // Store the count at the original index of a[]
            res.set(origIndex, ind);
        }

        return res;
    }

    public static void main(String[] args) {
        int[] a = {1, 2, 3, 4, 7, 9};
        int[] b = {0, 1, 2, 1, 1, 4};

        ArrayList<Integer> result = countLessEq(a, b);

        for (int count : result) {
            System.out.print(count + " ");
        }
    }
}
Python 
def countLessEq(a, b):
    n = len(a)
    m = len(b)

    # Result array to store counts, initialized with zeros
    res = [0] * n

    # Pair each element of a[] with its original index to preserve order
    aIndexed = [(val, idx) for idx, val in enumerate(a)]

    # Sort the paired array and b[]
    aIndexed.sort()
    b.sort()

    ind = 0  # Pointer for b[]

    # For each element in sorted a[]
    for val, originalIndex in aIndexed:
        
        # Move ind until b[ind] > current val
        while ind < m and b[ind] <= val:
            ind += 1
        # Store the count at the correct position
        res[originalIndex] = ind

    return res


# Driver Code
if __name__ == "__main__":
    a = [1, 2, 3, 4, 7, 9]
    b = [0, 1, 2, 1, 1, 4]
    result = countLessEq(a, b)
    
    print(" ".join(map(str, result)))
C# 
using System;
using System.Collections.Generic;

class GfG {

    public static List<int> countLessEq(int[] a, int[] b) {
        int n = a.Length, m = b.Length;

        // Result list initialized with zeros
        List<int> res = new List<int>(new int[n]);

        // Create a list of pairs (value, originalIndex) for array a[]
        List<(int val, int idx)> sortedA = new List<(int, int)>();
        for (int i = 0; i < n; i++) {
            sortedA.Add((a[i], i));
        }

        // Sort a[] based on values, and b[]
        sortedA.Sort((x, y) => x.val.CompareTo(y.val));
        Array.Sort(b);

        int ind = 0;

        // For each element in sorted a[]
        foreach (var item in sortedA) {
            int value = item.val;
            int originalIndex = item.idx;

            // Move ind while b[ind] <= value
            while (ind < m && b[ind] <= value) {
                ind++;
            }

            // Store count at the correct index
            res[originalIndex] = ind;
        }

        return res;
    }

    public static void Main(string[] args) {
        int[] a = {1, 2, 3, 4, 7, 9};
        int[] b = {0, 1, 2, 1, 1, 4};

        List<int> result = countLessEq(a, b);

        // Output the result
        foreach (int count in result) {
            Console.Write(count + " ");
        }
    }
}
JavaScript 
function countLessEq(a, b) {
    const n = a.length, m = b.length;

    // Result array initialized with zeros
    const res = new Array(n).fill(0);

    // Create a new array of pairs [value, originalIndex] for array a
    const sortedA = a.map((val, idx) => [val, idx]);

    // Sort sortedA by values and b[] in ascending order
    sortedA.sort((x, y) => x[0] - y[0]);
    b.sort((x, y) => x - y);

    let ind = 0; 

    // For each element in sortedA
    for (let i = 0; i < n; i++) {
        const [value, originalIndex] = sortedA[i];

        // Count how many elements in b[] are <= value
        while (ind < m && b[ind] <= value) {
            ind++;
        }

        // Store the result at the correct original index
        res[originalIndex] = ind;
    }

    return res;
}

// Driver Code
const a = [1, 2, 3, 4, 7, 9];
const b = [0, 1, 2, 1, 1, 4];

const result = countLessEq(a, b);
console.log(result.join(" "));

Output
4 5 5 6 6 6

[Expected Approach for Small Range] Using Count Array and Prefix Sum - O(n + m + max(b[i])) Time and O(max(b[i])) Space

The main idea is to first construct a frequency array for b[] to record how often each number appears. This frequency array is then transformed into a prefix sum array, where each index holds the total count of elements in b[] that are less than or equal to that index. With this preprocessed data, the count for any element in a[] can then be retrieved in constant time.

Illustration:

C++ 
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

vector<int> countLessEq(vector<int>& a, vector<int>& b) {
    
    int n = a.size(), m = b.size();

    // to store the result
    vector<int> res(n);
    
    int maxi = *max_element(b.begin(), b.end());
    
    // to store frequency of elements in b[]
    vector<int> cnt(maxi + 1, 0);
    for (int i = 0; i < m; i++) {
        cnt[b[i]]++;
    }

    // transform cnt[] to prefix sum array
    for (int i = 1; i < maxi+1; i++) {
        cnt[i] += cnt[i - 1];
    }

    // loop for each element of a[]
    for (int i = 0; i < n; i++) {
        res[i] = cnt[min(a[i], maxi)];
    }

    return res;
}

int main() {
    vector<int> a = {1, 2, 3, 4, 7, 9};
    vector<int> b = {0, 1, 2, 1, 1, 4};
    vector<int> result = countLessEq(a, b);
    for (int i : result) {
        cout << i << " ";
    }
    return 0;
}
Java 
import java.util.*;

class GfG {

    // to store the result
    public static ArrayList<Integer> countLessEq(int[] a, int[] b) {
        int n = a.length, m = b.length;
        
        int maxi = 0;
        // to store the result
        ArrayList<Integer> res = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            res.add(0);
        }
        
        for(int i=0;i<m;i++){
            maxi = Math.max(maxi, b[i]);
        }
        // to store frequency of elements in b[]
        int[] cnt = new int[maxi+1];
        for (int i = 0; i <= maxi; i++) {
            cnt[i] = 0;
        }
        for (int i = 0; i < m; i++) {
            cnt[b[i]]++;
        }

        // transform cnt[] to prefix sum array
        for (int i = 1; i <= maxi; i++) {
            cnt[i] += cnt[i - 1];
        }

        // loop for each element of a[]
        for (int i = 0; i < n; i++) {
            res.set(i, cnt[Math.min(a[i],maxi)]);
        }

        return res;
    }

    public static void main(String[] args) {
        int[] a = {1, 2, 3, 4, 7, 9};
        int[] b = {0, 1, 2, 1, 1, 4};
        ArrayList<Integer> result = countLessEq(a, b);
        for (int i : result) {
            System.out.print(i + " ");
        }
    }
}
Python 
# to store the result
def countLessEq(a, b):
    n = len(a)
    m = len(b)

    # to store the result
    res = [0] * n
    maxi = max(b)
    # to store frequency of elements in b[]
    cnt = [0] * (maxi + 1)
    
    for i in range(m):
        cnt[b[i]] += 1

    # transform cnt[] to prefix sum array
    for i in range(1, (maxi + 1)):
        cnt[i] += cnt[i - 1]

    # loop for each element of a[]
    for i in range(n):
        res[i] = cnt[min(a[i], maxi)]

    return res

if __name__ == "__main__":
    a = [1, 2, 3, 4, 7, 9]
    b = [0, 1, 2, 1, 1, 4]
    result = countLessEq(a, b)
    for i in result:
        print(i, end=" ")
C# 
using System;
using System.Collections.Generic;

class GfG {

    public static List<int> countLessEq(int[] a, int[] b) {
        int n = a.Length, m = b.Length;

        // to store the result
        List<int> res = new List<int>();
        for (int i = 0; i < n; i++) {
            res.Add(0);
        }
        int maxi = 0;
        
        for(int i=0;i<m;i++){
            maxi = Math.Max(maxi, b[i]);    
        }
        // to store frequency of elements in b[]
        int[] cnt = new int[maxi + 1];
        for (int i = 0; i < (maxi + 1); i++) {
            cnt[i] = 0;
        }
        for (int i = 0; i < m; i++) {
            cnt[b[i]]++;
        }

        // transform cnt[] to prefix sum array
        for (int i = 1; i < (maxi + 1); i++) {
            cnt[i] += cnt[i - 1];
        }

        // loop for each element of a[]
        for (int i = 0; i < n; i++) {
            res[i] = cnt[Math.Min(a[i], maxi)];
        }

        return res;
    }

    public static void Main(string[] args) {
        int[] a = {1, 2, 3, 4, 7, 9};
        int[] b = {0, 1, 2, 1, 1, 4};
        List<int> result = countLessEq(a, b);
        foreach (int i in result) {
            Console.Write(i + " ");
        }
    }
}
JavaScript 
function countLessEq(a, b) {
    let n = a.length, m = b.length;

    // to store the result
    let res = new Array(n).fill(0);
    
    let maxi = 0;
    
    for(let i=0;i<m;i++){
        maxi = Math.max(maxi, b[i]);
    }
    // to store frequency of elements in b[]
    let cnt = new Array(maxi + 1).fill(0);
    for (let i = 0; i < m; i++) {
        cnt[b[i]]++;
    }

    // transform cnt[] to prefix sum array
    for (let i = 1; i <= maxi; i++) {
        cnt[i] += cnt[i - 1];
    }

    // loop for each element of a[]
    for (let i = 0; i < n; i++) {
        res[i] = cnt[Math.min(a[i], maxi)];
    }

    return res;
}

// Driver Code
let a = [1, 2, 3, 4, 7, 9];
let b = [0, 1, 2, 1, 1, 4];
let result = countLessEq(a, b);
console.log(result.join(" "));

Output
4 5 5 6 6 6

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For each in 1st array count less than or equal to it in 2nd array

A

Ayush
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