Javascript Program to Count triplets with sum smaller than a given value

// A Simple Javascript program to count triplets with sum smaller
// than a given value
let arr = [5, 1, 3, 4, 7];

function countTriplets(n, sum) {

    // Initialize result
    let ans = 0;

    // Fix the first element as A[i]
    for (let i = 0; i < n - 2; i++) {
        // Fix the second element as A[j]
        for (let j = i + 1; j < n - 1; j++) {
            // Now look for the third number
            for (let k = j + 1; k < n; k++)
                if (arr[i] + arr[j] + arr[k] < sum)
                    ans++;
        }
    }
    return ans;
}

// Driver method to test the above function
let sum = 12;
console.log(countTriplets(arr.length, sum));

// A Simple Javascript program to count triplets with sum smaller
// than a given value
let arr = [5, 1, 3, 4, 7];

function countTriplets(n, sum) {

    // Sort input array
    arr.sort(function (a, b) { return b - a });

    // Initialize result
    let ans = 0;

    // Every iteration of loop counts triplet with
    // first element as arr[i].
    for (let i = 0; i < n - 2; i++) {

        // Initialize other two elements as corner elements
        // of subarray arr[j+1..k]
        let j = i + 1, k = n - 1;

        // Use Meet in the Middle concept
        while (j < k) {
            // If sum of current triplet is more or equal,
            // move right corner to look for smaller values
            if (arr[i] + arr[j] + arr[k] >= sum)
                k--;

            // Else move left corner
            else {

                // This is important. For current i and j, there
                // can be total k-j third elements.
                ans += (k - j);
                j++;
            }
        }
    }
    return ans;
}

// Driver method to test the above function
let sum = 12;
console.log(countTriplets(arr.length, sum));