Remove duplicates from a sorted array using STL in C++ Last Updated : 11 Jul, 2025 Comments Improve Suggest changes Like Article Like Report Given a sorted array, the task is to remove the duplicate elements from the array using STL in C++ Examples: Input: arr[] = {2, 2, 2, 2, 2} Output: arr[] = {2} Input: arr[] = {1, 2, 2, 3, 4, 4, 4, 5, 5} Output: arr[] = {1, 2, 3, 4, 5} Approach: The duplicates of the array can be removed using the unique() function provided in STL. Below is the implementation of the above approach. CPP #include <bits/stdc++.h> using namespace std; // Function to remove duplicate elements void removeDuplicates(int arr[], int n) { // Initialise a vector // to store the array values // and an iterator // to traverse this vector vector<int> v(arr, arr + n); vector<int>::iterator it; // using unique() method to remove duplicates it = unique(v.begin(), v.end()); // resize the new vector v.resize(distance(v.begin(), it)); // Print the array with duplicates removed cout << "\nAfter removing duplicates:\n"; for (it = v.begin(); it != v.end(); ++it) cout << *it << ", "; cout << '\n'; } // Driver code int main() { int arr[] = { 1, 2, 2, 3, 4, 4, 4, 5, 5 }; int n = sizeof(arr) / sizeof(arr[0]); // Print array cout << "\nBefore removing duplicates:\n"; for (int i = 0; i < n; i++) cout << arr[i] << " "; // call removeDuplicates() removeDuplicates(arr, n); return 0; } Output: Before removing duplicates: 1 2 2 3 4 4 4 5 5 After removing duplicates: 1, 2, 3, 4, 5, Comment More infoAdvertise with us Next Article Remove duplicates from an unsorted array using STL in C++ C code_r Follow Improve Article Tags : C++ STL cpp-array Practice Tags : CPPSTL Similar Reads Remove duplicates from an unsorted array using STL in C++ Given an unsorted array, the task is to remove the duplicate elements from the array using STL in C++ Examples: Input: arr[] = {1, 2, 5, 1, 7, 2, 4, 2} Output: arr[] = {1, 2, 4, 5, 7} Input: arr[] = {1, 2, 4, 3, 5, 4, 4, 2, 5} Output: arr[] = {1, 2, 3, 4, 5} Approach: The duplicates of the array can 2 min read Remove duplicates from an unsorted array using STL in C++ Given an unsorted array, the task is to remove the duplicate elements from the array using STL in C++ Examples: Input: arr[] = {1, 2, 5, 1, 7, 2, 4, 2} Output: arr[] = {1, 2, 4, 5, 7} Input: arr[] = {1, 2, 4, 3, 5, 4, 4, 2, 5} Output: arr[] = {1, 2, 3, 4, 5} Approach: The duplicates of the array can 2 min read Remove duplicates from an unsorted array using STL in C++ Given an unsorted array, the task is to remove the duplicate elements from the array using STL in C++ Examples: Input: arr[] = {1, 2, 5, 1, 7, 2, 4, 2} Output: arr[] = {1, 2, 4, 5, 7} Input: arr[] = {1, 2, 4, 3, 5, 4, 4, 2, 5} Output: arr[] = {1, 2, 3, 4, 5} Approach: The duplicates of the array can 2 min read Remove duplicate elements in an Array using STL in C++ Given an array, the task is to remove the duplicate elements from the array using STL in C++ Examples: Input: arr[] = {2, 2, 2, 2, 2} Output: arr[] = {2} Input: arr[] = {1, 2, 2, 3, 4, 4, 4, 5, 5} Output: arr[] = {1, 2, 3, 4, 5} Approach: This can be done using set in standard template library. Set 2 min read Remove duplicate elements in an Array using STL in C++ Given an array, the task is to remove the duplicate elements from the array using STL in C++ Examples: Input: arr[] = {2, 2, 2, 2, 2} Output: arr[] = {2} Input: arr[] = {1, 2, 2, 3, 4, 4, 4, 5, 5} Output: arr[] = {1, 2, 3, 4, 5} Approach: This can be done using set in standard template library. Set 2 min read Remove duplicate elements in an Array using STL in C++ Given an array, the task is to remove the duplicate elements from the array using STL in C++ Examples: Input: arr[] = {2, 2, 2, 2, 2} Output: arr[] = {2} Input: arr[] = {1, 2, 2, 3, 4, 4, 4, 5, 5} Output: arr[] = {1, 2, 3, 4, 5} Approach: This can be done using set in standard template library. Set 2 min read Like