[Swift]LeetCode593. 有效的正方形 | Valid Square

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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:

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

---

给定二维空间中四点的坐标，返回四点是否可以构造一个正方形。

一个点的坐标（x，y）由一个有两个整数的整数数组表示。

示例:

输入: p1 = [0,0], p2 = [1,1], p3 = [1,0], p4 = [0,1]
输出: True 

注意:

1. 所有输入整数都在 [-10000，10000] 范围内。
2. 一个有效的正方形有四个等长的正长和四个等角（90度角）。
3. 输入点没有顺序。

---

Runtime: 8 ms

Memory Usage: 19.2 MB

class Solution {
    func validSquare(_ p1: [Int], _ p2: [Int], _ p3: [Int], _ p4: [Int]) -> Bool {
        var s:Set<Int> = [d(p1, p2), d(p1, p3), d(p1, p4), d(p2, p3), d(p2, p4), d(p3, p4)]
        return !s.contains(0) && s.count == 2
    }
    
    func d(_ p1:[Int],_ p2:[Int]) -> Int
    {
         return (p1[0] - p2[0]) * (p1[0] - p2[0]) + (p1[1] - p2[1]) * (p1[1] - p2[1])        
    }
}

---

12ms

class Solution {
    func validSquare(_ p1: [Int], _ p2: [Int], _ p3: [Int], _ p4: [Int]) -> Bool {
        var dict = [Int: Int]()
        let distances = [dist(p1, p2), dist(p1, p3), dist(p1, p4), dist(p2, p3), dist(p2, p4), dist(p3, p4)]
        var maxDist = -1
        for dist in distances {
            maxDist = max(maxDist, dist)
            dict[dist] = dict[dist, default: 0] + 1
        }
        if (dict[maxDist] == 2 && dict.count == 2) {
            return true
        }
        return false
    }
    
    func dist(_ p1: [Int], _ p2: [Int]) -> Int {
        return (p1[0]-p2[0]) * (p1[0]-p2[0]) + (p1[1]-p2[1]) * (p1[1]-p2[1])
    }
}

---

16ms

import Foundation

class Solution {
    func validSquare(_ p1: [Int], _ p2: [Int], _ p3: [Int], _ p4: [Int]) -> Bool {       
        let points : [[Int]] = [p1,p2,p3,p4]
        var totalsum = 0
        var sums : [Double] = []
        
        if Set(points).count != points.count {
            return false
        }
        
        func get_distance(_ d1:[Int],_ d2: [Int]) -> Double {
            let dist = sqrt(pow((Double(d1[0])-Double(d2[0])),2)+pow((Double(d1[1])-Double(d2[1])),2))
            return dist
        }
        
        for i in Range(0...points.count - 1) {
            if i == points.count - 1 {
                break
            }
            for j in Range(i+1...points.count - 1) {
                let d = get_distance(points[i],points[j])
                sums.append(d)
            }
        }
        if Set(sums).count == 2 {
            return true
        } else {
            return false
        }
    }
}

---

20ms

class Solution {
    func validSquare(_ p1: [Int], _ p2: [Int], _ p3: [Int], _ p4: [Int]) -> Bool {
        
        var distanceArray: [Int] = []
        
        distanceArray.append(distanceBetween(p1: p1, p2: p2))
        distanceArray.append(distanceBetween(p1: p1, p2: p3))
        distanceArray.append(distanceBetween(p1: p1, p2: p4))
        distanceArray.append(distanceBetween(p1: p2, p2: p3))
        distanceArray.append(distanceBetween(p1: p2, p2: p4))
        distanceArray.append(distanceBetween(p1: p3, p2: p4))
        
        distanceArray.sort()
        
        if distanceArray[0] > 0
            , distanceArray[0] == distanceArray[1]
            , distanceArray[1] == distanceArray[2]
            , distanceArray[2] == distanceArray[3]
            , distanceArray[4] == distanceArray[5] {
            return true
        } else {
            return false
        }
    }
    
    private func distanceBetween(p1: [Int], p2: [Int]) -> Int {
        let deltaX = p2.first! - p1.first!
        let deltaY = p2.last! - p1.last!
        return deltaX * deltaX + deltaY * deltaY
    }
}