LeetCode_最接近的三數之和_Array_M

16. 最接近的三數之和

class Solution {
    public int threeSumClosest(int[] nums, int target) {
        if (nums.length < 3) {
            return -1;
        }
        Arrays.sort(nums);
        int res = nums[0] + nums[1] + nums[2];
        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 (Math.abs(res - target) > Math.abs(sum - target)) {   // 當前有更靠近的結果
                    res = sum;
                }
                if (sum == target) {    // 找到相等的了
                    return sum;
                } else if (sum > target) {  // 移動遊標
                    while (l < r && nums[r] == nums[r - 1]) r--;
                    r--;
                } else {
                    while (l < r && nums[l] == nums[l + 1]) l++;
                    l++;
                }
            }
        }
        return res;
    }
}