19.1.26 [LeetCode16] 3Sum Closest

Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

Example:

Given array nums = [-1, 2, 1, -4], and target = 1.

The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

题意

跟15差不多，这次是找到最接近给定target的3个数的和

题解

class Solution {
public:
    int threeSumClosest(vector<int>& nums, int target) {
        sort(nums.begin(), nums.end());
        int tmp=nums[0]+nums[1]+nums[2];
        for (int i = 0; i < nums.size(); i++) {
            int j = i + 1, k = nums.size() - 1;
            while (j < k) {
                int tt = nums[i] + nums[j] + nums[k];
                if (abs(tmp - target) > abs(tt - target))
                    tmp = tt;
                if (tt < target)j++;
                else if (tt == target)return target;
                else k--;
            }
        }
        return tmp;
    }
};

解法也基本相同