LeetCode16——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).

难度系数： 中等

实现：

int threeSumClosest(vector &num, int target) {
    std::sort(num.begin(), num.end());
    int closestVal = INT_MAX;
    int closestSum = 0;
    int small, big;
    for (int i = 0; i < num.size() - 2; ++i){
        small = i+1;
        big = num.size()-1;
        while (small < big) {
            int sum = num[small] + num[big] + num[i];
            int absVal = abs(sum - target);
            if (absVal < closestVal) {
                closestVal = absVal;
                closestSum = sum;
                cout << closestSum << endl;
            }
            if (sum > target) {
                big--;
            } else {
                small++;
            }
        }
    }
    return closestSum;
}