Add solution #752

Author: JoshCrozier

README.md

@@ -570,6 +570,7 @@
 747|[Largest Number At Least Twice of Others](./0747-largest-number-at-least-twice-of-others.js)|Easy|
 748|[Shortest Completing Word](./0748-shortest-completing-word.js)|Easy|
 749|[Contain Virus](./0749-contain-virus.js)|Hard|
+752|[Open the Lock](./0752-open-the-lock.js)|Medium|
 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|
 783|[Minimum Distance Between BST Nodes](./0783-minimum-distance-between-bst-nodes.js)|Easy|

solutions/0752-open-the-lock.js

@@ -0,0 +1,54 @@
+/**
+ * 752. Open the Lock
+ * https://leetcode.com/problems/open-the-lock/
+ * Difficulty: Medium
+ *
+ * You have a lock in front of you with 4 circular wheels. Each wheel has 10 slots: '0', '1', '2',
+ * '3', '4', '5', '6', '7', '8', '9'. The wheels can rotate freely and wrap around: for example
+ * we can turn '9' to be '0', or '0' to be '9'. Each move consists of turning one wheel one slot.
+ *
+ * The lock initially starts at '0000', a string representing the state of the 4 wheels.
+ *
+ * You are given a list of deadends dead ends, meaning if the lock displays any of these codes,
+ * the wheels of the lock will stop turning and you will be unable to open it.
+ *
+ * Given a target representing the value of the wheels that will unlock the lock, return the
+ * minimum total number of turns required to open the lock, or -1 if it is impossible.
+ */
+
+/**
+ * @param {string[]} deadends
+ * @param {string} target
+ * @return {number}
+ */
+var openLock = function(deadends, target) {
+  const dead = new Set(deadends);
+  const queue = [['0000', 0]];
+  const seen = new Set(['0000']);
+
+  if (dead.has('0000')) return -1;
+  while (queue.length) {
+    const [combo, turns] = queue.shift();
+    if (combo === target) return turns;
+
+    for (let i = 0; i < 4; i++) {
+      const current = combo[i];
+      const up = (parseInt(current) + 1) % 10;
+      const down = (parseInt(current) + 9) % 10;
+
+      const nextUp = combo.slice(0, i) + up + combo.slice(i + 1);
+      if (!seen.has(nextUp) && !dead.has(nextUp)) {
+        queue.push([nextUp, turns + 1]);
+        seen.add(nextUp);
+      }
+
+      const nextDown = combo.slice(0, i) + down + combo.slice(i + 1);
+      if (!seen.has(nextDown) && !dead.has(nextDown)) {
+        queue.push([nextDown, turns + 1]);
+        seen.add(nextDown);
+      }
+    }
+  }
+
+  return -1;
+};