Add solution #936

Author: JoshCrozier

README.md

@@ -745,6 +745,7 @@
 933|[Number of Recent Calls](./solutions/0933-number-of-recent-calls.js)|Easy|
 934|[Shortest Bridge](./solutions/0934-shortest-bridge.js)|Medium|
 935|[Knight Dialer](./solutions/0935-knight-dialer.js)|Medium|
+936|[Stamping The Sequence](./solutions/0936-stamping-the-sequence.js)|Hard|
 937|[Reorder Data in Log Files](./solutions/0937-reorder-data-in-log-files.js)|Medium|
 966|[Vowel Spellchecker](./solutions/0966-vowel-spellchecker.js)|Medium|
 970|[Powerful Integers](./solutions/0970-powerful-integers.js)|Easy|

solutions/0936-stamping-the-sequence.js

@@ -0,0 +1,78 @@
+/**
+ * 936. Stamping The Sequence
+ * https://leetcode.com/problems/stamping-the-sequence/
+ * Difficulty: Hard
+ *
+ * You are given two strings stamp and target. Initially, there is a string s of length
+ * target.length with all s[i] == '?'.
+ *
+ * In one turn, you can place stamp over s and replace every letter in the s with the
+ * corresponding letter from stamp.
+ *
+ * For example, if stamp = "abc" and target = "abcba", then s is "?????" initially.
+ * In one turn you can:
+ * - place stamp at index 0 of s to obtain "abc??",
+ * - place stamp at index 1 of s to obtain "?abc?", or
+ * - place stamp at index 2 of s to obtain "??abc".
+ *
+ * Note that stamp must be fully contained in the boundaries of s in order to stamp
+ * (i.e., you cannot place stamp at index 3 of s).
+ *
+ * We want to convert s to target using at most 10 * target.length turns.
+ *
+ * Return an array of the index of the left-most letter being stamped at each turn. If we
+ * cannot obtain target from s within 10 * target.length turns, return an empty array.
+ */
+
+/**
+ * @param {string} stamp
+ * @param {string} target
+ * @return {number[]}
+ */
+var movesToStamp = function(stamp, target) {
+  const stampLength = stamp.length;
+  const targetLength = target.length;
+  const moves = [];
+  const targetArray = target.split('');
+  let totalReplaced = 0;
+
+  function tryStampAt(position) {
+    let canStamp = false;
+    let hasUnstamped = false;
+
+    for (let i = 0; i < stampLength; i++) {
+      const currentChar = targetArray[position + i];
+      if (currentChar === '?') continue;
+      if (currentChar !== stamp[i]) return false;
+      hasUnstamped = true;
+    }
+
+    if (hasUnstamped) {
+      for (let i = 0; i < stampLength; i++) {
+        if (targetArray[position + i] !== '?') {
+          targetArray[position + i] = '?';
+          totalReplaced++;
+        }
+      }
+      canStamp = true;
+    }
+
+    return canStamp;
+  }
+
+  const maxMoves = 10 * targetLength;
+  while (moves.length <= maxMoves) {
+    let madeChange = false;
+    for (let i = 0; i <= targetLength - stampLength; i++) {
+      if (tryStampAt(i)) {
+        moves.push(i);
+        madeChange = true;
+        break;
+      }
+    }
+    if (!madeChange) break;
+    if (totalReplaced === targetLength) return moves.reverse();
+  }
+
+  return [];
+};