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authorJack Sangdahl <[email protected]>2025-06-14 23:06:55 -0600
committerJack Sangdahl <[email protected]>2025-06-14 23:06:55 -0600
commit5195299ad94c2d75650e2698994ba271cfc6e72e (patch)
treecead2a441a352aa8f913e3e71832ce76506dd17a /valid_square.c
parentd39bae7e2e70b5658e96204f9bd61f4e7cb25d48 (diff)
downloadleetcode-5195299ad94c2d75650e2698994ba271cfc6e72e.tar.gz
leetcode-5195299ad94c2d75650e2698994ba271cfc6e72e.zip
593. valid square
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+// 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
+}