Add solution #765

Author: JoshCrozier

0765-couples-holding-hands.js

@@ -0,0 +1,46 @@
+/**
+ * 765. Couples Holding Hands
+ * https://leetcode.com/problems/couples-holding-hands/
+ * Difficulty: Hard
+ *
+ * There are n couples sitting in 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 ith 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.
+ */
+
+/**
+ * @param {number[]} row
+ * @return {number}
+ */
+function minSwapsCouples(row) {
+  const n = row.length / 2;
+  const partner = new Array(2 * n);
+  const position = new Array(2 * n);
+
+  for (let i = 0; i < 2 * n; i++) {
+    partner[i] = i % 2 === 0 ? i + 1 : i - 1;
+    position[row[i]] = i;
+  }
+
+  let swaps = 0;
+  for (let i = 0; i < 2 * n; i += 2) {
+    const current = row[i];
+    const expected = partner[current];
+    const nextPerson = row[i + 1];
+
+    if (nextPerson !== expected) {
+      row[i + 1] = expected;
+      row[position[expected]] = nextPerson;
+      position[nextPerson] = position[expected];
+      position[expected] = i + 1;
+      swaps++;
+    }
+  }
+
+  return swaps;
+}

README.md

@@ -579,6 +579,7 @@
 762|[Prime Number of Set Bits in Binary Representation](./0762-prime-number-of-set-bits-in-binary-representation.js)|Easy|
 763|[Partition Labels](./0763-partition-labels.js)|Medium|
 764|[Largest Plus Sign](./0764-largest-plus-sign.js)|Medium|
+765|[Couples Holding Hands](./0765-couples-holding-hands.js)|Hard|
 783|[Minimum Distance Between BST Nodes](./0783-minimum-distance-between-bst-nodes.js)|Easy|
 784|[Letter Case Permutation](./0784-letter-case-permutation.js)|Medium|
 790|[Domino and Tromino Tiling](./0790-domino-and-tromino-tiling.js)|Medium|