D4_1224_계산기3.java

package com.swea.D4;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Stack;

public class D4_1224_계산기3 {

    private static int getPriority(char c) {
        switch (c) {
            case '*':
            case '/':
                return 1;
            case '+':
            case '-':
                return 0;
        }
        return -1;
    }

    private static String toPostFix(String infix) {
        StringBuilder sb = new StringBuilder();
        char[] chars = infix.toCharArray();
        Stack<Character> stack = new Stack<>();
        final int SIZE = chars.length;

        char temp;
        for (int i = 0; i < SIZE; ++i) {
            temp = chars[i];
            int w = getPriority(temp);

            if (temp == '*' || temp == '/' || temp == '+' || temp == '-') {
                while (!stack.isEmpty() && getPriority(stack.peek()) >= w) {
                    sb.append(stack.pop());
                }
                stack.push(temp);
            } else if (temp == '(') {
                stack.push(temp);
            } else if (temp == ')') {
                while (!stack.isEmpty() && stack.peek() != '(') {
                    sb.append(stack.pop());
                }
                stack.pop();
            } else {
                sb.append(temp);
            }
        }
        return sb.toString();
    }

    private static long calculate(String postfix) {
        Stack<Long> stack = new Stack<>();
        char[] chars = postfix.toCharArray();
        char temp;
        final int SIZE = chars.length;
        long value1 = 0;
        long value2 = 0;

        for (int i = 0; i < SIZE; ++i) {
            temp = chars[i];
            if (Character.isDigit(temp)) stack.push(new Long(temp - '0'));
            else {
                value2 = stack.pop();
                value1 = stack.pop();
                switch (temp) {
                    case '*':
                        stack.push(value1 * value2);
                        break;
                    case '/':
                        stack.push(value1 / value2);
                        break;
                    case '+':
                        stack.push(value1 + value2);
                        break;
                    case '-':
                        stack.push(value1 - value2);
                        break;
                }
            }
        }
        return stack.pop();
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br1 = new BufferedReader(new InputStreamReader(System.in));
        BufferedReader br = new BufferedReader(new FileReader("C:\\intelliJ_workspaces\\Algorithm\\src\\com\\swea\\D4\\testcase\\1224input.txt"));
        for (int t = 1; t <= 10; ++t) {
            br.readLine();
            System.out.println("#" + t + " " + calculate(toPostFix(br.readLine())));
        }
    }
}