leetcodeOJ 16. 3Sum Closest

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).

与leetcodeOJ 15题相似，需要多维护一个最小值diff，

代码如下：

class Solution {public:    int threeSumClosest(vector<int>& nums, int target) {        if(nums.size() < 3)            return INT_MAX;                int ans = 0;        sort(nums.begin(), nums.end());        int diff = abs(nums[0] + nums[1] + nums[2] - target);        for(int i = 0; i < nums.size(); i++){            if(i > 0 && nums[i] == nums[i-1])                continue;                        int left = i+1;            int right = nums.size()-1;                        while(left < right){                int temp = nums[i] + nums[left] + nums[right];                if(abs(target - temp) <= diff){                    diff = abs(target - temp);                    ans = temp;                   // cout << ans << " " << diff << endl;                }                if(temp > target){                    right--;                    while(left < right && nums[right] == nums[right+1]){                        right--;                    }                }                else if(temp < target){                    left++;                    while(left < right && nums[left] == nums[left-1]){                        left++;                    }                }                else if(temp == target){                    return target;                }                                            }                    }                return ans;    }};