🎨 Day 19

Author: AkashRajpurohit

README.md

@@ -27,6 +27,7 @@
 2. [Longest Mountain in Array](https://leetcode.com/explore/challenge/card/november-leetcoding-challenge/566/week-3-november-15th-november-21st/3533/) ➡️ [CPP Solution](Week3/longestMountain.cpp)
 3. [Mirror Reflection](https://leetcode.com/explore/challenge/card/november-leetcoding-challenge/566/week-3-november-15th-november-21st/3534/) ➡️ [CPP Solution](Week3/mirrorReflection.cpp)
 4. [Merge Intervals](https://leetcode.com/explore/challenge/card/november-leetcoding-challenge/566/week-3-november-15th-november-21st/3535/) ➡️ [CPP Solution](Week3/merge.cpp)
+5. [Decode String](https://leetcode.com/explore/challenge/card/november-leetcoding-challenge/566/week-3-november-15th-november-21st/3536/) ➡️ [CPP Solution](Week3/decodeString.cpp)
 
 ## Week 4 🚧
 Coming soon...

Week3/decodeString.cpp

@@ -0,0 +1,41 @@
+class Solution {
+public:
+    string decodeString(string s) {
+        stack<int> numStack;
+        stack<string> strStack;
+        
+        string str = "";
+        int num = 0;
+        
+        for(char c: s) {
+            
+            if(isdigit(c)) {
+                num = num * 10 + (c - '0');
+            } else if(c == '[') {
+                strStack.push(str);
+                str = "";
+                
+                numStack.push(num);
+                num = 0;
+            } else if(c == ']') {
+                string temp = str;
+                
+                str = strStack.top();
+                strStack.pop();
+                
+                int count = numStack.top();
+                numStack.pop();
+                
+                while(count-- > 0) {
+                    str.append(temp);
+                }
+                
+            } else {
+                str += c;
+            }
+            
+        }
+        
+        return str;
+    }
+};