[LeetCode] (medium) 593. Valid Square

原创于 2019-05-23 16:48:01 发布 · 239 阅读

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博客给出LeetCode题目链接，要求根据二维空间中四个点的坐标，判断这四点能否构成正方形。点的坐标用含两个整数的数组表示，输入整数范围在[-10000, 10000]，有效正方形需四边等长且四角为90度，输入点无顺序要求。

https://leetcode.com/problems/valid-square/

Given the coordinates of four points in 2D space, return whether the four points could construct a square.

The coordinate (x,y) of a point is represented by an integer array with two integers.

Example:
Input: p1 = [0,0], p2 = [1,1], p3 = [1,0], p4 = [0,1]
Output: True
Note:

All the input integers are in the range [-10000, 10000].
A valid square has four equal sides with positive length and four equal angles (90-degree angles).
Input points have no order.

class Solution {
public:
    bool validSquare(vector<int>& p1, vector<int>& p2, vector<int>& p3, vector<int>& p4) {
        unordered_set<int> S({dist(p1, p2), dist(p1, p3), dist(p1, p4), dist(p2, p3), dist(p2, p4), dist(p3, p4)});
        return S.find(0) == S.end() && S.size() == 2;
    }
    
    int dist(vector<int> &p1, vector<int> &p2){
        return (p1[0]-p2[0])*(p1[0]-p2[0]) + (p1[1]-p2[1])*(p1[1]-p2[1]);
    }
};