Add solution #556

Author: JoshCrozier

README.md

@@ -440,6 +440,7 @@
 552|[Student Attendance Record II](./0552-student-attendance-record-ii.js)|Hard|
 553|[Optimal Division](./0553-optimal-division.js)|Medium|
 554|[Brick Wall](./0554-brick-wall.js)|Medium|
+556|[Next Greater Element III](./0556-next-greater-element-iii.js)|Medium|
 557|[Reverse Words in a String III](./0557-reverse-words-in-a-string-iii.js)|Easy|
 560|[Subarray Sum Equals K](./0560-subarray-sum-equals-k.js)|Medium|
 563|[Binary Tree Tilt](./0563-binary-tree-tilt.js)|Easy|

solutions/0556-next-greater-element-iii.js

@@ -0,0 +1,38 @@
+/**
+ * 556. Next Greater Element III
+ * https://leetcode.com/problems/next-greater-element-iii/
+ * Difficulty: Medium
+ *
+ * Given a positive integer n, find the smallest integer which has exactly the same digits existing
+ * in the integer n and is greater in value than n. If no such positive integer exists, return -1.
+ *
+ * Note that the returned integer should fit in 32-bit integer, if there is a valid answer but it
+ * does not fit in 32-bit integer, return -1.
+ */
+
+/**
+ * @param {number} n
+ * @return {number}
+ */
+var nextGreaterElement = function(n) {
+  const digits = [...String(n)];
+  let i = digits.length - 2;
+
+  while (i >= 0 && digits[i] >= digits[i + 1]) i--;
+  if (i < 0) return -1;
+
+  let j = digits.length - 1;
+  while (j >= 0 && digits[j] <= digits[i]) j--;
+
+  [digits[i], digits[j]] = [digits[j], digits[i]];
+  let left = i + 1;
+  let right = digits.length - 1;
+  while (left < right) {
+    [digits[left], digits[right]] = [digits[right], digits[left]];
+    left++;
+    right--;
+  }
+
+  const result = +digits.join('');
+  return result > n && result <= 2**31 - 1 ? result : -1;
+};