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| 1 | +package LeetCodeJava.Math; |
| 2 | + |
| 3 | +// https://leetcode.com/problems/valid-square/description/ |
| 4 | + |
| 5 | +import java.util.Arrays; |
| 6 | + |
| 7 | +/** |
| 8 | + * 593. Valid Square Attempted Medium Topics Companies Given the coordinates of four points in 2D |
| 9 | + * space p1, p2, p3 and p4, return true if the four points construct a square. |
| 10 | + * |
| 11 | + * <p>The coordinate of a point pi is represented as [xi, yi]. The input is not given in any order. |
| 12 | + * |
| 13 | + * <p>A valid square has four equal sides with positive length and four equal angles (90-degree |
| 14 | + * angles). |
| 15 | + * |
| 16 | + * <p>Example 1: |
| 17 | + * |
| 18 | + * <p>Input: p1 = [0,0], p2 = [1,1], p3 = [1,0], p4 = [0,1] Output: true Example 2: |
| 19 | + * |
| 20 | + * <p>Input: p1 = [0,0], p2 = [1,1], p3 = [1,0], p4 = [0,12] Output: false Example 3: |
| 21 | + * |
| 22 | + * <p>Input: p1 = [1,0], p2 = [-1,0], p3 = [0,1], p4 = [0,-1] Output: true |
| 23 | + * |
| 24 | + * <p>Constraints: |
| 25 | + * |
| 26 | + * <p>p1.length == p2.length == p3.length == p4.length == 2 -104 <= xi, yi <= 104 |
| 27 | + */ |
| 28 | +public class ValidSquare { |
| 29 | + |
| 30 | + // V0 |
| 31 | + // TODO : implement |
| 32 | + // public boolean validSquare(int[] p1, int[] p2, int[] p3, int[] p4) { |
| 33 | + // |
| 34 | + // } |
| 35 | + |
| 36 | + // V1 |
| 37 | + // https://leetcode.com/problems/valid-square/editorial/ |
| 38 | + // IDEA : BRUTE FORCE |
| 39 | + public double dist(int[] p1, int[] p2) { |
| 40 | + return (p2[1] - p1[1]) * (p2[1] - p1[1]) + (p2[0] - p1[0]) * (p2[0] - p1[0]); |
| 41 | + } |
| 42 | + |
| 43 | + public boolean check(int[] p1, int[] p2, int[] p3, int[] p4) { |
| 44 | + return dist(p1, p2) > 0 |
| 45 | + && dist(p1, p2) == dist(p2, p3) |
| 46 | + && dist(p2, p3) == dist(p3, p4) |
| 47 | + && dist(p3, p4) == dist(p4, p1) |
| 48 | + && dist(p1, p3) == dist(p2, p4); |
| 49 | + } |
| 50 | + |
| 51 | + public boolean validSquare_1(int[] p1, int[] p2, int[] p3, int[] p4) { |
| 52 | + int[][] p = {p1, p2, p3, p4}; |
| 53 | + return checkAllPermutations(p, 0); |
| 54 | + } |
| 55 | + |
| 56 | + boolean checkAllPermutations(int[][] p, int l) { |
| 57 | + if (l == 4) { |
| 58 | + return check(p[0], p[1], p[2], p[3]); |
| 59 | + } else { |
| 60 | + boolean res = false; |
| 61 | + for (int i = l; i < 4; i++) { |
| 62 | + swap(p, l, i); |
| 63 | + res |= checkAllPermutations(p, l + 1); |
| 64 | + swap(p, l, i); |
| 65 | + } |
| 66 | + return res; |
| 67 | + } |
| 68 | + } |
| 69 | + |
| 70 | + public void swap(int[][] p, int x, int y) { |
| 71 | + int[] temp = p[x]; |
| 72 | + p[x] = p[y]; |
| 73 | + p[y] = temp; |
| 74 | + } |
| 75 | + |
| 76 | + // V2 |
| 77 | + // https://leetcode.com/problems/valid-square/editorial/ |
| 78 | + // IDEA : Using Sorting |
| 79 | + public double dist_2(int[] p1, int[] p2) { |
| 80 | + return (p2[1] - p1[1]) * (p2[1] - p1[1]) + (p2[0] - p1[0]) * (p2[0] - p1[0]); |
| 81 | + } |
| 82 | + |
| 83 | + public boolean validSquare_2(int[] p1, int[] p2, int[] p3, int[] p4) { |
| 84 | + int[][] p = {p1, p2, p3, p4}; |
| 85 | + Arrays.sort(p, (l1, l2) -> l2[0] == l1[0] ? l1[1] - l2[1] : l1[0] - l2[0]); |
| 86 | + return dist_2(p[0], p[1]) != 0 |
| 87 | + && dist_2(p[0], p[1]) == dist_2(p[1], p[3]) |
| 88 | + && dist_2(p[1], p[3]) == dist_2(p[3], p[2]) |
| 89 | + && dist_2(p[3], p[2]) == dist_2(p[2], p[0]) |
| 90 | + && dist_2(p[0], p[3]) == dist_2(p[1], p[2]); |
| 91 | + } |
| 92 | + |
| 93 | + // V3 |
| 94 | + // https://leetcode.com/problems/valid-square/editorial/ |
| 95 | + // IDEA : Checking every case |
| 96 | + public double dist_3(int[] p1, int[] p2) { |
| 97 | + return (p2[1] - p1[1]) * (p2[1] - p1[1]) + (p2[0] - p1[0]) * (p2[0] - p1[0]); |
| 98 | + } |
| 99 | + |
| 100 | + public boolean check_3(int[] p1, int[] p2, int[] p3, int[] p4) { |
| 101 | + return dist_3(p1, p2) > 0 |
| 102 | + && dist_3(p1, p2) == dist_3(p2, p3) |
| 103 | + && dist_3(p2, p3) == dist_3(p3, p4) |
| 104 | + && dist_3(p3, p4) == dist_3(p4, p1) |
| 105 | + && dist_3(p1, p3) == dist_3(p2, p4); |
| 106 | + } |
| 107 | + |
| 108 | + public boolean validSquare_3(int[] p1, int[] p2, int[] p3, int[] p4) { |
| 109 | + return check_3(p1, p2, p3, p4) || check_3(p1, p3, p2, p4) || check_3(p1, p2, p4, p3); |
| 110 | + } |
| 111 | +} |
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