leetcode16. 最接近的三数之和

和三数之和很类似，同理排序后固定第一个数，然后双指针即可，同时根据差值的绝对值是否更小决定是否更新返回的res

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