Runtime: 56 ms (Top 86.81%) | Memory: 51.10 MB (Top 5.49%)

Author: AnasImloul

scripts/algorithms/R/Remove Duplicate Letters/Remove Duplicate Letters.js

@@ -1,8 +1,34 @@
+// Runtime: 56 ms (Top 86.81%) | Memory: 51.10 MB (Top 5.49%)
+
+/**
+ * @param {string} s
+ * @return {string}
+ */
 var removeDuplicateLetters = function(s) {
-    let sset = [...new Set(s)]
-    if(Math.min(sset) == sset[0]) return [...sset].join('');
-    else {
-        sset.sort();
-        return [...sset].join('');
+    const lastOccurrence = {};
+    for (let i = 0; i < s.length; i++) {
+        lastOccurrence[s[i]] = i;
     }
+
+    const stack = [];
+    const visited = new Set();
+
+    for (let i = 0; i < s.length; i++) {
+        if (visited.has(s[i])) {
+            continue;
+        }
+
+        while (
+            stack.length > 0 &&
+            s[i] < stack[stack.length - 1] &&
+            i < lastOccurrence[stack[stack.length - 1]]
+        ) {
+            visited.delete(stack.pop());
+        }
+
+        visited.add(s[i]);
+        stack.push(s[i]);
+    }
+
+    return stack.join('');    
 };