16. 3Sum Closest

LeetCode

My Solution (Two Pointers)

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class Solution {
    public int threeSumClosest(int[] nums, int target) {
        int diff = Integer.MAX_VALUE;
        int sign = 1;
        int n = nums.length;

        Arrays.sort(nums);


        for (int i = 0; i < n - 2; i++) {
            int l = i + 1;
            int r = n - 1;
            while(l < r) {
                int sum = nums[i] + nums[l] + nums[r];
                if (Math.abs(sum - target) < diff) {
                    diff = Math.abs(sum - target);
                    if (sum > target) {
                        sign = 1;
                    } else {
                        sign = -1;
                    }
                }
                if (sum > target) {
                    r--;
                } else {
                    l++;
                }
            }

        }

        return target + diff * sign;
    }
}

Remarks:

  1. Instead of sign, just use a closest sum:

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    if (Math.abs(sum - target) < Math.abs(closestSum - target)) {
        closestSum = sum;
    }