// 593. Valid Square #include "leetcode.h" /* * given the coordinates of four points in a 2d space 'p1 .. p4', return true if * the four points oncstruct a square. the coordinate of a point 'p_i' is * represented as '[x_i, y_i]'. the input is not given in any order. a valid * square has four equal sides with positive length and four equal angles * (90-degree angles) */ int dist(int x, int y) { return x * x + y * y; } bool validSquare(int *p1, int p1Size, int *p2, int p2Size, int *p3, int p3Size, int *p4, int p4Size) { int *p[4] = {p1, p2, p3, p4}, e[2] = {0}; for (int i = 0; i < 4; i++) { for (int j = i + 1; j < 4; j++) { int n = dist(p[i][0] - p[j][0], p[i][1] - p[j][1]); if (!n) return false; if (n == e[0] || (!e[0] && n != e[1])) e[0] = n; else if (n == e[1] || (!e[1] && n != e[0])) e[1] = n; else return false; } } return true; } int main() { int p11[] = {0, 0}, p21[] = {1, 1}, p31[] = {1, 0}, p41[] = {0, 1}; int p12[] = {0, 0}, p22[] = {1, 1}, p32[] = {1, 0}, p42[] = {0, 12}; int p13[] = {1, 0}, p23[] = {-1, 0}, p33[] = {0, 1}, p43[] = {0, -1}; printf("%d\n", validSquare(p11, ARRAY_SIZE(p11), p21, ARRAY_SIZE(p21), p31, ARRAY_SIZE(p31), p41, ARRAY_SIZE(p41))); // expect: 1 printf("%d\n", validSquare(p12, ARRAY_SIZE(p12), p22, ARRAY_SIZE(p22), p32, ARRAY_SIZE(p32), p42, ARRAY_SIZE(p42))); // expect: 0 printf("%d\n", validSquare(p13, ARRAY_SIZE(p13), p23, ARRAY_SIZE(p23), p33, ARRAY_SIZE(p33), p43, ARRAY_SIZE(p43))); // expect: 1 }