一. Array
1. 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).
**思路:先排序,然后按照顺序举出所有可能。
代码:**
class Solution {
public:
int threeSumClosest(vector<int>& nums, int target) {
sort(nums.begin(),nums.end());
int minDis=INT_MAX;
int out=0;
for(int i=0;i<nums.size()-2;i++){
int l=i+1,r=nums.size()-1;
while(l<r){
int sum=nums[i];
sum+=(nums[l]+nums[r]);
if(sum==target){out=target;return target;}
if(sum<target){l++;minDis=min(minDis,target-sum);if(minDis==target-sum)out=sum;}
if(sum>target){r--;minDis=min(minDis,sum-target);if(minDis==sum-target)out=sum;}
}
}
return out;
}
};