LeetCode 16 3Sum Closest

LeetCode 16 3Sum Closest

Description

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).

解题思路

和上一题差不多。

代码

class Solution {
public:
int threeSumClosest(vector<int> &num, int target) {
int ans = num[0] + num[1] + num[2];
sort(num.begin(), num.end());
for (int i = 0; i <= num.size(); i++) {
int a = i + 1;
int b = (int) num.size() - 1;
while (a < b) {
int sum = num[i] + num[a] + num[b];
if (abs(sum - target) < abs(ans - target))
ans = sum;
if (sum < target)
++a;
else if (sum > target)
--b;
else {
break;
}
}
}
return ans;
}
};