Add solution #484

Author: JoshCrozier

README.md

@@ -472,6 +472,7 @@
 481|[Magical String](./solutions/0481-magical-string.js)|Medium|
 482|[License Key Formatting](./solutions/0482-license-key-formatting.js)|Easy|
 483|[Smallest Good Base](./solutions/0483-smallest-good-base.js)|Hard|
+484|[Find Permutation](./solutions/0484-find-permutation.js)|Medium|
 485|[Max Consecutive Ones](./solutions/0485-max-consecutive-ones.js)|Easy|
 486|[Predict the Winner](./solutions/0486-predict-the-winner.js)|Medium|
 488|[Zuma Game](./solutions/0488-zuma-game.js)|Hard|

solutions/0484-find-permutation.js

@@ -0,0 +1,39 @@
+/**
+ * 484. Find Permutation
+ * https://leetcode.com/problems/find-permutation/
+ * Difficulty: Medium
+ *
+ * A permutation perm of n integers of all the integers in the range [1, n] can be
+ * represented as a string s of length n - 1 where:
+ * - s[i] == 'I' if perm[i] < perm[i + 1], and
+ * - s[i] == 'D' if perm[i] > perm[i + 1].
+ *
+ * Given a string s, reconstruct the lexicographically smallest permutation perm and return it.
+ */
+
+/**
+ * @param {string} s
+ * @return {number[]}
+ */
+var findPermutation = function(s) {
+  const n = s.length + 1;
+  const result = new Array(n).fill(0).map((_, i) => i + 1);
+
+  for (let i = 0; i < s.length; i++) {
+    if (s[i] === 'D') {
+      let start = i;
+      while (i < s.length && s[i] === 'D') {
+        i++;
+      }
+      let end = i;
+      while (start < end) {
+        [result[start], result[end]] = [result[end], result[start]];
+        start++;
+        end--;
+      }
+      i--;
+    }
+  }
+
+  return result;
+};