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authorjack <[email protected]>2024-06-14 13:13:15 -0600
committerjack <[email protected]>2024-06-14 13:13:15 -0600
commitd343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa (patch)
tree96df922dae2a5073d9a50ea70c7aae6aa37e3ebe /couples_holding_hands.c
downloadleetcode-d343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa.tar.gz
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+// 765. Couples Holding Hands
+#include <stdio.h>
+#include <stdlib.h>
+
+/*
+ * there are 'n' couples sitting '2n' seats arranged in a row and want to hold
+ * hands. the people and seats are represented by an integer array 'row' where
+ * 'row[i]' is the id of the person sitting in the i'th seat. the couples are
+ * numbered in order, the first couple being '(0, 1)', the second couple being
+ * '(2, 3)', and so on with the last couple being '(2n -2, 2n -1)'. return the
+ * minimum number of swaps so that every couple is sitting side by side. a swap
+ * consists of choosing any two people then they stand up and switch seats.
+ */
+
+int minSwapsCouples(int *row, int row_size) {
+ int pair[60], position[60], cnt = 0;
+ for (int i = 0; i < 60; i += 2) {
+ pair[i] = i + 1;
+ pair[i + 1] = i;
+ }
+ for (int i = 0; i < row_size; i++)
+ position[row[i]] = i;
+ for (int i = 0; i < row_size; i += 2) {
+ if (row[i + 1] != pair[row[i]]) {
+ cnt++;
+ int pos = position[pair[row[i]]];
+ position[row[i + 1]] = pos;
+ int tmp = row[pos];
+ row[pos] = row[i + 1];
+ row[i + 1] = tmp;
+ position[pair[row[i]]] = i + 1;
+ }
+ }
+ return cnt;
+}
+
+int main() {
+ int r1[] = {0, 2, 1, 3}, r2[] = {3, 2, 0, 1};
+ printf("%d\n", minSwapsCouples(r1, 4)); // expect: 1
+ printf("%d\n", minSwapsCouples(r2, 4)); // expect: 0
+}