Javascript Program for Least frequent element in an array

// JavaScript program to find the least frequent element
// in an array.

function leastFrequent(arr, n) {

    // Sort the array
    arr.sort();

    // find the min frequency using 
    // linear traversal
    let min_count = n + 1, res = -1;
    let curr_count = 1;

    for (let i = 1; i < n; i++) {
        if (arr[i] == arr[i - 1])
            curr_count++;
        else {
            if (curr_count < min_count) {
                min_count = curr_count;
                res = arr[i - 1];
            }

            curr_count = 1;
        }
    }

    // If last element is least frequent
    if (curr_count < min_count) {
        min_count = curr_count;
        res = arr[n - 1];
    }

    return res;
}

// Driver code

let arr = [1, 3, 2, 1, 2, 2, 3, 1];
let n = arr.length;
console.log(leastFrequent(arr, n));

// JavaScript program to find the least frequent element
// in an array.

function leastFrequent(arr, n) {
    // Insert all elements in hash.
    let hash = new Map();
    for (let i = 0; i < n; i++) {
        if (hash.has(arr[i]))
            hash.set(arr[i], hash.get(arr[i]) + 1)
        else
            hash.set(arr[i], 1);
    }

    // find the min frequency
    let min_count = n + 1, res = -1;

    hash.forEach((value, key) => {

        if (min_count >= value) {
            res = key;
            min_count = value;
        }
    });

    return res;
}

// driver program
let arr = [1, 3, 2, 1, 2, 2, 3, 1];
let n = arr.length;
console.log(leastFrequent(arr, n));