leetcode question 16: 3Sum Closest

问题：
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).

这道题简单点说就是求随意取三个数，其和要与目标值的差的绝对值最小。借鉴了 3Sum 的解法，我先进行排序，然后遍历取3个数字求和，找出绝对值差最小的和，简单粗暴。下面是代码：class Solution {
public:
int threeSumClosest(vector<int>& nums, int target) {
int diff = -1;
int answer;
sort(nums.begin(), nums.end());

for (int i = 0; i < nums.size(); i++) {
for (int j = i + 1; j < nums.size(); j++) {
int k = nums.size() - 1;

while (j < k) {
if (diff == -1 || diff > abs(nums[i] + nums[j] + nums[k] - target)) {
answer = nums[i] + nums[j] + nums[k];
diff = abs(answer - target);
}
k--;
}
}
}

return answer;
}
};