题解 | #四则运算#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNext()) { // 注意 while 处理多个 case
            String str = in.nextLine();
            System.out.println(v(str));
        }
//        System.out.println(sum("3/-1+2"));
    }

    private static String sum(String sub) {
        if (sub.startsWith("-")) {
            sub = "0" + sub;
        }
        Deque<String> deque = new LinkedList<>();
        List<String> list = init(sub.trim());

        String token = "";
        for (int i = 0; i < list.size(); i++) {
            token = list.get(i);
            if (token.equals("*")) {
                String left = deque.pop();
                String right = list.get(i + 1);
                token = String.valueOf(Integer.parseInt(left) * Integer.parseInt(right));
                deque.push(token);
                i++;
            } else if (token.equals("/")) {
                String left = deque.pop();
                String right = list.get(i + 1);
                token = String.valueOf(Integer.parseInt(left) / Integer.parseInt(right));
                deque.push(token);
                i++;
            } else {
                deque.push(token);
            }
        }

        while (deque.size() > 1) {
            String left = deque.removeLast();
            String op = deque.removeLast();
            String right = deque.removeLast();
            if (op.equals("+")) {
                token = String.valueOf(Integer.parseInt(left) + Integer.parseInt(right));
            }
            if (op.equals("-")) {
                token = String.valueOf(Integer.parseInt(left) - Integer.parseInt(right));
            }
            deque.addLast(token);
        }

        return deque.pop();
    }

    private static List<String> init(String sub) {
        List<String> list = new LinkedList<>();
        String val = "";
        char last = 0;
        char ch = 0;
        int symbol = 1;
        for (int i = 0; i < sub.length(); i++) {
            last = ch;
            ch = sub.charAt(i);
            int num = 0;
            if (ch == '-') {
                if (last == '*' || last == '/' || last == '+' || last == '-' || last == 0) {
                    symbol = -1;
                    continue;
                } else if (Character.isDigit(last)) {

                }
            }
            if (Character.isDigit(ch)) {
                while (Character.isDigit(ch)) {
                    num = num*10 + Integer.parseInt(ch+ "");
                    ++i;
                    if (sub.length() > i) {
                        ch = sub.charAt(i);
                    } else {
                        break;
                    }
                }
                i--;
                ch = sub.charAt(i);
                val = symbol * num + "";
                symbol = 1;

            } else {
                val = ch + "";
            }
            list.add(val);
        }
        return list;
    }

    /**
     9+3-5-10-2*10*(10+3+(4*1-10+5)-(9*5*1+5-7))
     2+(4*5+1)*8+7*4+10-9+3+1*9-(6-0*4*4)
     (7+4*3+10*(3-3+4-1-8-10))
     -3+9*6*(6-10-2)
     -3*(-1)
     (3-1)
     3+-1
     * @param str
     * @return
     */
    private static String v(String str) {
        String sub = "";
        String re = "";
        for (int i = 0; re.length() == 0; i++) {
            if (str.contains("(")) {
                int start = str.lastIndexOf("(");
                int end = str.indexOf(")", start);
                sub = str.substring(start + 1, end);
                String reg = "(" + sub + ")";
                str = str.replace(reg, sum(sub));
            } else if (str.contains("[")) {
                int start = str.lastIndexOf("[");
                int end = str.indexOf("]", start);
                sub = str.substring(start + 1, end);
                String reg = "[" + sub + "]";
                str = str.replace(reg, sum(sub));
            } else if (str.contains("{")) {
                int start = str.lastIndexOf("{");
                int end = str.indexOf("}", start);
                sub = str.substring(start + 1, end);
                String reg = "{" + sub + "}";
                str = str.replace(reg, sum(sub));
            } else {
                re = sum(str);
            }
        }

        return re;
    }

}