各种括号题

// recursive way
#include <iostream>
#include <sstream>
#include <string>
using namespace std;

int calculate(stringstream& ss) {
    int res = 0, sign = 1;
    while(ss) {
        if(isdigit(ss.peek())) {
            int val;
            ss >> val;
            res += sign * val;
            continue;
        }
        char ch;
        ss >> ch;
        if(ch == ‘)‘) {
            return res;
        }
        if(ch == ‘(‘) {
            res += sign * calculate(ss);
        }
        if(ch == ‘-‘) {
            sign = -1;
        }
        if(ch == ‘+‘) {
            sign = 1;
        }
    }
    return res;
} 

int calculate(string&& s) {
    stringstream ss;
    ss << std::noskipws << s;
    return calculate(ss);
}



int main()
{
  cout << calculate("0") << endl;
}

// Example program
#include <iostream>
#include <sstream>
#include <string>
using namespace std;

int calculate(stringstream& ss) {
    int res = 0, left = 0;
    char ch = ‘+‘;
    while(ss) {
        int right = 0;
        ss >> std::ws;  
        if(isdigit(ss.peek()) || ss.peek() == ‘(‘) {
            if(ss.peek() == ‘(‘) {
                ss.get();//ignore ‘(‘
                right = calculate(ss);
            }else {          
                ss >> right;
            }
            if(ch == ‘+‘ || ch == ‘-‘) {
                res += left;
                left = (ch == ‘+‘)? right : -right;
            }else {
                left = ((ch == ‘*‘) ? left * right : left / right); 
            }
            continue;
        }
        ss >> ch;
        if(ch == ‘)‘) {
            return res + left;
        }
    }
    return res + left;
} 

int calculate(string&& s) {
    stringstream ss;
    ss << s;
    return calculate(ss);
}

int main()
{
  cout << calculate("1+(9+8)*(7+8*3+(9+8)*6)+(8-7)*5+6") << endl;
}