blueprint

import java.util.Stack;

public class infixToPostfixx{

    // mo check ni kong ang Char kay operator
    private boolean isOperator(char c) {
        return c == '+' || c == '-' || c == '*' || c == '/';
    }

     // precedence sa mga operators
    private int precedence(char c) {
        if (c == '+' || c == '-') {
            return 1;
        }
        if (c == '*' || c == '/') {
            return 2;
        }
        return -1;
    }

    //convert infix to postfix
    public String infixToPostfix(String expression) {
        Stack<Character> stack = new Stack<>();
        StringBuilder postfix = new StringBuilder();
        StringBuilder numberBuffer = new StringBuilder(); // Handle multi-digit numbers

        for (int i = 0; i < expression.length(); i++) {
            char c = expression.charAt(i);

            // kong digit gani e accumulate ang number
            if (Character.isDigit(c)) {
                numberBuffer.append(c);
                continue;
            }

           //gi add ang number to the postfix Expression
            if (numberBuffer.length() > 0) {
                postfix.append(numberBuffer).append(' ');
                numberBuffer.setLength(0);  // Clear the buffer
            }

            // Push '(' onto the stack
            if (c == '(') {
                stack.push(c);
                continue;
            }

            // Pop operators until '(' is found
            if (c == ')') {
                while (!stack.isEmpty() && stack.peek() != '(') {
                    postfix.append(stack.pop()).append(' ');
                }
                stack.pop(); // Remove '('
                continue;
            }

            // Handle operators
            if (isOperator(c)) {
                while (!stack.isEmpty() && precedence(c) <= precedence(stack.peek())) {
                    postfix.append(stack.pop()).append(' ');
                }
                stack.push(c);
            }
        }

       // mo add sa mga numbers kong naa mn
        if (numberBuffer.length() > 0) {
            postfix.append(numberBuffer).append(' ');
        }

        //mo pop sa mga remaining operators
        while (!stack.isEmpty()) {
            postfix.append(stack.pop()).append(' ');
        }

        return postfix.toString().trim();  // Return the postfix result
    }

    public static void main(String[] args) {
        infixToPostfixx converter = new infixToPostfixx();
        String infix = " 10 * 2 / 5 (8 - 1)";
        System.out.println("Postfix Expression: " + converter.infixToPostfix(infix));
    }
}