GFG PTOD | 07 Jan 2025 | Pair with given sum in a sorted array

int countPairs(vector<int> &arr, int target) {
        // Complete the function
        int count = 0, i=0, j=arr.size()-1;
        while(i<j) {
            int sum = arr[i] + arr[j];
            if(sum < target) i++;
            else if(sum > target) j--;
            else {
                int el1 = arr[i], el2=arr[j];
                int ci = 0, cj=0;
                
                while(arr[i] == el1 && i<=j) ci++, i++;
                while(arr[j] == el2 && i<=j) cj++, j--;
                
                if(el1 == el2) count += ci*(ci-1)/2;
                else count += ci*cj; 
            }
        }
        return count;
    }