LeetCode16 3Sum Closest

题意：

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. (Medium)

    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).

分析：

　　排序、遍历方式顺序与3 sum思路一致，维护一个与target的差值即可。

代码：

 class Solution {

 public:

     int threeSumClosest(vector<int>& nums, int target) {

         sort(nums.begin(), nums.end());

         int diff = 0x7FFFFFFF;

         for (int i = ; i < nums.size() - ; ++i) {

             int start = i + , end = nums.size() - ;

             while (start < end) {

                 int curSum = nums[i] + nums[start] + nums[end];

                 if (curSum - target == ) {

                     return target;

                 }

                 else if (curSum - target > ) {

                     if (curSum- target < abs(diff) ) {

                         diff = curSum - target;

                     }

                     end--;

                 }

                 else {

                     if (target - curSum < abs(diff)) {

                         diff = curSum - target;

                     }

                     start++;

                 }

             }

         }

         return diff + target;

     }

 };

巴特西

LeetCode16 3Sum Closest

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