每日算法系列【LeetCode 16】最接近的三数之和

输入：
nums = [-1，2，1，-4], target = 1.
输出：
2
解释：
与 target 最接近的三个数的和为 2. (-1 + 2 + 1 = 2).

class Solution {
public:
    int threeSumClosest(vector<int>& nums, int target) {
        int n = nums.size(), res = 10000000;
        sort(nums.begin(), nums.end());
        for (int i = 0; i < n - 2; ++i) {
            int l = i + 1, r = n - 1;
            while (l < r) {
                int sum = nums[i] + nums[l] + nums[r];
                if (sum == target) return sum;
                if (abs(sum-target) < abs(res-target)) res = sum;
                if (sum > target) r--;
                else l++;
            }
        }
        return res;
    }
};

class Solution:
    def threeSumClosest(self, nums: List[int], target: int) -> int:
        n, res = len(nums), 10000000
        nums.sort()
        for i in range(n-2):
            l, r = i+1, n-1
            while l < r:
                s = nums[i] + nums[l] + nums[r]
                if s == target:
                    return s
                if abs(s-target) < abs(res-target):
                    res = s
                if s > target:
                    r -= 1
                else:
                    l += 1
        return res