Infix to Prefix Conversion using Stack

Infix expression ko Prefix (Polish Notation) me convert karne ke liye hum standard Shunting-Yard algorithm ko ek smart 4-step transformation pipeline ke saath adapt karte hain.

4-Step Conversion Pipeline

1. Step 1 (Reverse): Given Infix string ko completely reverse karein.
2. Step 2 (Swap Parentheses): Reversed string me har '(' ko ')' aur har ')' ko '(' me convert karein.
3. Step 3 (Modified Postfix Conversion): Ab is transformed string par Infix to Postfix conversion apply karein (Note: agar equal precedence ho toh right-associative rule follow karein).
4. Step 4 (Final Reverse): Jo postfix result mile, use wapas reverse kar dein. Yeh final Prefix expression ban jayega!

Solved Example

Infix: (A + B) * C

• Step 1 (Reverse): C * ) B + A (
• Step 2 (Swap Parentheses): C * ( B + A )
• Step 3 (Postfix Conversion):
  • Scan C -> Output: C
  • Scan * -> Stack: *
  • Scan ( -> Stack: * (
  • Scan B -> Output: C B
  • Scan + -> Stack: * ( +
  • Scan A -> Output: C B A
  • Scan ) -> Pop + -> Output: C B A +, discard (
  • End scan -> Pop * -> Output: C B A + *
• Step 4 (Reverse Output): * + A B C

Hence, Prefix Expression: * + A B C.

Agli post me hum cover karenge Evaluation of Postfix Expression using Stack.