GFG PTOD | 08 Jan 2025 | Count the number of possible triangles

int countTriangles(vector<int>& arr) {
        // code here
        int count = 0;
        sort(arr.begin(), arr.end());
        for(int i=2; i<arr.size(); i++) {
            int j=0, k=i-1;
            while(j<k) {
                if(arr[j]+arr[k] > arr[i]) {
                    count += k-j;
                    k--;
                } else {
                    j++;
                }
            }
        }
        return count;
    }