3 Sum Smaller

Given an array of n integers nums and a target, find the number of index triplets i, j, k with 0 <= i < j < k < n that satisfy the condition nums[i] + nums[j] + nums[k] < target.

• Time: O(n^2)
• Space: O(1)

public int threeSumSmaller(int[] nums, int target) {
    Arrays.sort(nums);
    int count = 0;
    for (int i = 0; i < nums.length - 2; i++) {
        int l = i + 1, r = nums.length - 1;
        while (l < r) {
            int sum = nums[i] + nums[l] + nums[r];
            if (sum < target) {
                l++;
                count += r - l;
            } else {
                r--;
            }
        }
    }
    return count;
}