Today's Learning: Conversion from Infix to Postfix and Conversion from Prefix to Infix
Hello everyone!
Today, I worked on two very interesting problems that dealt with expressions and the use of stacks. Here's what I did:
Conversion of Infix to Postfix using Stack:
I started with the problem of converting an infix expression like A + B * C to a postfix expression like A B C * +. Infix expressions are the standard way of writing mathematical expressions, but to evaluate them one needs to know operator precedence and parentheses. Postfix notation eliminates the need for parentheses and operator precedence, making it easier to evaluate.
I followed this approach, using a stack to assist in managing the operators and operands:
Scanned the infix expression from left to right.
Whenever I encountered an operand (like A, B, or C), I added it directly to the result.
When I encountered an operator-like +, -, *, or /, I pushed it onto the stack. But before doing so, I checked whether the operator already on top of the stack has a higher precedence. If true, I popped it onto the result first.
I also balanced parentheses, so that operators inside the parentheses are evaluated before those outside. Finally, the stack contained the remaining operators, which I popped into the result to complete the conversion.
Prefix to Infix Conversion:
Then I coded the conversion of a prefix expression like + A * B C to an infix expression such as (A + (B * C)). Problem was read the prefix expression from right to left, convert to valid infix expression.
Steps
I scanned prefix expression from right to left.
If ever I found operand then push it on a stack.
I simply popped the top two operands off of the stack, formed a new expression by placing the operator between them, and pushed the result back onto the stack. At the end, the stack contains the final infix expression which I can print or return.
I hope my experience is helpful.
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