给定一个有 n 个整数的数组 S,找出 S 中 3 个数,使其和等于一个给定的数,target。
返回这 3 个数的和,你可以假定每个输入都有且只有一个结果。
例如,给定 S = {-1 2 1 -4},和 target = 1。
那么最接近 target 的和是 2。(-1 + 2 + 1 = 2)。
Given an array S of n integers,
find three integers in S such that the sum is closest to a given number, target.
Return the sum of the three integers.
You may assume that each input would have exactly one solution.
For example, given array S = {-1 2 1 -4}, and target = 1.
The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
也许我已经开始体会到上一题中别人写的方法的思想了。
在这个题目中,我们要做以下几件事:
class Solution { public: int threeSumClosest(vector<int>& nums, int target) { sort(nums.begin(), nums.end()); int len = nums.size(); int result = INT_MAX, close = INT_MAX; for (int current = 0; current < len - 2; current++) { int front = current + 1, back = len - 1; while (front < back) { int sum = nums[current] + nums[front] + nums[back]; if (sum < target) { if (target - sum < close) { close = target - sum; result = sum; } front++; } else if (sum > target) { if (sum - target < close) { close = sum - target; result = sum; } back--; } else { close = 0; result = target; do { front++; } while (front < back&&nums[front - 1] == nums[front]); do { back--; } while (front < back&&nums[back + 1] == nums[back]); } } while (current < len - 2 && nums[current + 1] == nums[current]) { current++; } } return result; } };
和本道题关联密切的题目推荐: