LeetCode #939 - Minimum Area Rectangle

题目描述：

Given a set of points in the xy-plane, determine the minimum area of a rectangle formed from these points, with sides parallel to the x and y axes.

If there isn't any rectangle, return 0.

Example 1:

Input: [[1,1],[1,3],[3,1],[3,3],[2,2]]

Output: 4

Example 2:

Input: [[1,1],[1,3],[3,1],[3,3],[4,1],[4,3]]

Output: 2

Note:

1. 1 <= points.length <= 500

2. 0 <= points[i][0] <= 40000

3. 0 <= points[i][1] <= 40000

4. All points are distinct.

class Solution {
public:
    int minAreaRect(vector>& points) {
        unordered_map hash;
        // unordered_map不支持用pair做key，所以为了映射xy坐标，可以令(x*40001+y)做key，因为x/y<=40000
        for(int i=0;i