Add solution #1081

Author: JoshCrozier

README.md

@@ -193,6 +193,7 @@
 1022|[Sum of Root To Leaf Binary Numbers](./1022-sum-of-root-to-leaf-binary-numbers.js)|Easy|
 1037|[Valid Boomerang](./1037-valid-boomerang.js)|Easy|
 1041|[Robot Bounded In Circle](./1041-robot-bounded-in-circle.js)|Medium|
+1081|[Smallest Subsequence of Distinct Characters](./1081-smallest-subsequence-of-distinct-characters.js)|Medium|
 1103|[Distribute Candies to People](./1103-distribute-candies-to-people.js)|Easy|
 1108|[Defanging an IP Address](./1108-defanging-an-ip-address.js)|Easy|
 1189|[Maximum Number of Balloons](./1189-maximum-number-of-balloons.js)|Easy|

solutions/1081-smallest-subsequence-of-distinct-characters.js

@@ -0,0 +1,29 @@
+/**
+ * 1081. Smallest Subsequence of Distinct Characters
+ * https://leetcode.com/problems/smallest-subsequence-of-distinct-characters/
+ * Difficulty: Medium
+ *
+ * Given a string s, return the lexicographically smallest subsequence
+ * of s that contains all the distinct characters of s exactly once.
+ */
+
+/**
+ * @param {string} s
+ * @return {string}
+ */
+var smallestSubsequence = function(s) {
+  const stack = [];
+
+  for (let i = 0; i < s.length; i++) {
+    const letter = s[i];
+    if (stack.indexOf(letter) > -1) {
+      continue;
+    }
+    while (stack.length > 0 && stack[stack.length - 1] > letter && s.indexOf(stack[stack.length - 1], i) > i) {
+      stack.pop();
+    }
+    stack.push(letter);
+  }
+
+  return stack.join('');
+};