Solved problem 150 : Evaluate Reverse Polish Notation

racoelhosilva · racoelhosilva · commit bad715651a86 · 2024-02-09T12:23:53.000Z
diff --git a/README.md b/README.md
@@ -16,7 +16,7 @@
 
 ### Problems Solved
 
-| Total | 59 |
+| Total | 60 |
 |:---:|:---:|
 
 #### Search By Topic
@@ -38,7 +38,7 @@
 | Math & Geometry | 4 |
 | Priority Queue | 3 |
 | Sliding Window | 2 |
-| Stack | 2 |
+| Stack | 3 |
 | Tries | 0 |
 | Two Pointers | 6 |
 
@@ -47,7 +47,7 @@
 | Difficulty | Number |
 |:---|---:|
 | Easy | 48 |
-| Medium | 11 |
+| Medium | 12 |
 | Hard | 0 |
 
 ## Milestones
diff --git a/Stack/Medium/150_EvaluateReversePolishNotation.cpp b/Stack/Medium/150_EvaluateReversePolishNotation.cpp
@@ -0,0 +1,44 @@
+/* 
+ * Problem: 150 
+ * Name: Evaluate Reverse Polish Notation
+ * Difficulty: Medium
+ * Topic: Stack
+ * Link: https://leetcode.com/problems/evaluate-reverse-polish-notation/
+ */
+ 
+#include <bits/stdc++.h>
+using namespace std;
+
+//      Stack Structure
+// Time Complexity: O(n)
+// Space Complexity: O(n)
+int evalRPN(vector<string>& tokens) {
+    stack<int> values;
+    
+    for (const string& s : tokens) {
+        if (s == "+"){
+            int a = values.top(); values.pop();
+            int b = values.top(); values.pop();
+            values.push(b + a);
+        }
+        else if (s == "-"){
+            int a = values.top(); values.pop();
+            int b = values.top(); values.pop();
+            values.push(b - a);
+        }
+        else if (s == "*"){
+            int a = values.top(); values.pop();
+            int b = values.top(); values.pop();
+            values.push(b * a);            
+        }
+        else if (s == "/"){
+            int a = values.top(); values.pop();
+            int b = values.top(); values.pop();
+            values.push(b / a);            
+        }
+        else {
+            values.push(stoi(s));
+        }
+    }
+    return values.top();
+}
