Problem
题目大意:给你四个点判断能否构成正方形。
https://leetcode.com/problems/valid-square/description/
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.
Solution
Time complexity: O(1)
Space complexity: O(1)
C++
1 2 3 4 5 6 7 8 9 10 11 12 13 |
// Author: Huahua // Running time: 8 ms class Solution { public: bool validSquare(vector<int>& p1, vector<int>& p2, vector<int>& p3, vector<int>& p4) { set<int> s{distSqr(p1, p2), distSqr(p1, p3), distSqr(p1, p4), distSqr(p2, p3), distSqr(p2, p4), distSqr(p3, p4)}; return !s.count(0) && s.size() == 2; } private: static inline int distSqr(const vector<int>& p1, const vector<int>& p2) { return (p1[0] - p2[0]) * (p1[0] - p2[0]) + (p1[1] - p2[1]) * (p1[1] - p2[1]); } }; |