四则运算（含括号）C++

输入一个表达式（用字符串表示），求这个表达式的值。

保证字符串中的有效字符包括[‘0’-‘9’],‘+’,‘-’, ‘*’,‘/’ ,‘(’， ‘)’,‘[’, ‘]’,‘{’ ,‘}’。且表达式一定合法。

数据范围：表达式计算结果和过程中满足 |val| \le 1000 \∣val∣≤1000  ，字符串长度满足 1 \le n \le 1000 \1≤n≤1000 

输入描述：

输入一个算术表达式

输出描述：

得到计算结果

示例1

输入：

3+2*{1+2*[-4/(8-6)+7]}

输出：

25

#include<iostream>
#include<vector>
#include<string>
#include<limits.h>
using namespace std;
int zuo=0, you=0;
bool isshu(string s){//判断字符串是否为数字
    if (s[0] <= '9' && s[0] >= '0')return true;
    if (s[0] = '-' && s.size() > 1)return true;
    return false;
}
int jisuan(vector<string> x) {         //计算没有括号的式子；
    vector <int> a; string w = ""; int b,c;
    for (int i = 0; i < x.size(); ++i) {
        if (x[i] == " ")continue;
        if (isshu(x[i]))a.push_back(stoi(x[i]));
        if (x[i] == "*") {
            while (!isshu(x[i])) {
                if (x[i] == "-") {
                    c = a.back(); a.pop_back();
                    a.push_back(INT_MIN);
                    a.push_back(c);
                }
                ++i;
            }
            b = stoi(x[i]);
            c = a.back() * b;
            a.pop_back();
            a.push_back(c);
        }
        if (x[i] == "/") {
            while (!isshu(x[i])) {
                if (x[i] == "-") {
                    c = a.back(); a.pop_back();
                    a.push_back(INT_MIN);
                    a.push_back(c);
                }
                ++i;
            }
            b = stoi(x[i]);
            c = a.back() / b;
            a.pop_back();
            a.push_back(c);
        }
        if (x[i] == "-")a.push_back(INT_MIN);
    }
    b = 0;
    for (int i = 0; i < a.size(); ++i) {
        if (a[i] == INT_MIN) {
            a[i] = 0;
            ++i;
            a[i] = -a[i];
        }
    }
    for (int i = 0; i < a.size(); ++i) {
        b += a[i];
    }
    return b;
}
bool kh(vector<string> x) {         //判断是否有括号，如果有，记录第一个完整括号的左右括号位置；
    for (int i = 0; i < x.size(); ++i) {
        if (x[i] == "{" || x[i] == "(" || x[i] == "[")zuo = i;
        else  if (x[i] == "}" || x[i] == ")" || x[i] == "]") {
            you = i;
            return true;
        }
    }
    return false;
}
int youkuohao(vector<string> x) {
    vector<string>b; int aw;
    while (kh(x)) {//如果有括号，计算括号内式子，并将值代替原括号；
        b.assign(x.begin() + zuo+1, x.begin() + you);
        aw = jisuan(b);
        x[zuo] = to_string(aw);
        for (int i = zuo + 1; i <= you;++i)x[i] = " ";
    }
    aw = jisuan(x);
    return aw;
}
int main() 
{
    string s,w="",c="";  vector<string>ss;//ss把s里在一起的数字当做一个整数
        cin >> s;
        for (int i = 0; i < s.size(); ++i) {
            if (s[i] <= '9' && s[i] >= '0') {
                w += s[i];
            }
            else
            {
                if(w!="")ss.push_back(w);
                w = ""; c += s[i];
                ss.push_back(c);
                c = "";
            }
        }
        ss.push_back(w);
        int a = youkuohao(ss);
        cout << a << endl;
    return 0;
}