Create program.cpp

Author: praxton74

Reverse Polish Notation/program.cpp

@@ -0,0 +1,34 @@
+class Solution {
+public:
+    int evalRPN(vector<string>& tokens)
+    {
+        stack<long>stk;
+        for(int i=0;i<tokens.size();i++)
+        {
+            if(tokens[i]!="+" && tokens[i]!="/" && tokens[i]!="*" && tokens[i]!="-")
+            {
+                long t=stoi(tokens[i]);
+                stk.push(t);
+            }
+            else
+            {
+                long a=stk.top();
+                stk.pop();
+                long b=stk.top();
+                stk.pop();
+                string ch=tokens[i];
+                long c=0;
+                if(ch=="+")
+                c=b+a;
+                if(ch=="-")
+                c=b-a;
+                if(ch=="*")
+                c=b*a;
+                if(ch=="/")
+                c=b/a;
+                stk.push(c);
+            }
+        }
+        return int(stk.top());    
+    }
+};