✨ Postfix ➡️ Prefix Converter in C++ 🚀

CPP/Stacks_Queues/postfixToPrefix.cpp

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+#include <iostream>
+#include <string>
+#include <stack>
+using namespace std;
+
+// Function to convert postfix expression to prefix
+string postfixToPrefix(string s){
+    int n = s.size();          // length of the postfix expression
+    stack<string> st;          // stack to store intermediate strings
+
+    int i = 0;                 
+    while(i < n){
+        // If current character is an operand (letter or digit)
+        if((s[i]>='a' && s[i]<='z') || 
+           (s[i]>='A' && s[i]<='Z') || 
+           (s[i]>='0' && s[i]<='9')){
+            // Push operand as a string onto the stack
+            st.push(string(1, s[i]));
+        }
+        else{
+            // If current character is an operator
+            // Pop top two operands from stack
+            string right = st.top(); st.pop();  // right operand
+            string left = st.top(); st.pop();  // left operand
+
+            // Concatenate operator + left operand + right operand
+            // and push back to stack
+            st.push(string(1, s[i]) + left + right);
+        }
+        i++;
+    }
+
+    // Final element of stack is the prefix expression
+    return st.top();
+}
+
+int main(){
+    string s = "AB-DE+F*/";          // example postfix expression
+    string ans = postfixToPrefix(s); // convert to prefix
+    cout << ans << endl;             // output prefix expression
+    return 0;
+}