dùng string c++ plssssssssssssssssss

#include <bits/stdc++.h>
using namespace std;

int bt(char op)
{
  if (op == '+' || op == '-')
    return 1;
  if (op == '*' || op == '/')
    return 2;
  return 0;
}

int cc(int a, int b, char op)
{
  switch (op)
  {
  case '+':
    return a + b;
  case '-':
    return a - b;
  case '*':
    return a * b;
  case '/':
    return a / b;
  }
}

int tong(string t)
{
  int i;
  stack<int> c;
  stack<char> ops;
  for (i = 0; i < t.length(); i++)
  {
    if (t[i] == ' ')
      continue;
    else if (isdigit(t[i]))
    {
      int ans = 0;
      while (i < t.length() && isdigit(t[i]))
      {
        ans = (ans * 10) + (t[i] - '0');
        i++;
      }
      c.push(ans);
      i--;
    }
    else
    {
      while (!ops.empty() && bt(ops.top()) >= bt(t[i]))
      {
        int ans2 = c.top();
        c.pop();
        int ans1 = c.top();
        c.pop();
        char op = ops.top();
        ops.pop();
        c.push(cc(ans1, ans2, op));
      }
      ops.push(t[i]);
    }
  }
  while (!ops.empty())
  {
    int ans2 = c.top();
    c.pop();
    int ans1 = c.top();
    c.pop();
    char op = ops.top();
    ops.pop();
    c.push(cc(ans1, ans2, op));
  }
  return c.top();
}

int main()
{
  freopen("bieuthuc.inp" , "r" , stdin);
  freopen("bieuthuc.out" , "w" , stdout);
  string s;
  cin >> s;
  cout << tong(s);
  return 0;
}

#include<bits/stdc++.h>
#define ll long long
using namespace std;

int tim1(char s){
    if (s=='+' || s=='-') return 1;
    if (s=='*') return 2;
    return 0;
}

int tim(int a,int b,char s){
    switch (s){
        case '+':return a+b;
        case '-':return a-b;
        case '*':return a*b;
    }
    return 0;
}

int check(const string& s){
    stack<int>x;
    stack<char>y;
    for (int i=0; i<s.length(); i++){
        if (isdigit(s[i])){
            x.push(s[i]-'0');
        }else{
            while (!y.empty() && tim1(y.top())>=tim1(s[i])){
                int a=x.top();
                x.pop();
                int b=x.top();
                x.pop();
                char c=y.top();
                y.pop();
                x.push(tim(b, a, c));
            }
            y.push(s[i]);
        }
    }
    while (!y.empty()){
        int a=x.top();
        x.pop();
        int b=x.top();
        x.pop();
        char c=y.top();
        y.pop();
        x.push(tim(b, a, c));
    }
    return x.top();
}

int main(){
    freopen("BIEUTHUC.inp","r",stdin);
    freopen("BIEUTHUC.out","w",stdout);
    string s;
    cin>>s;
    //meothinhle
    int res=check(s);
    cout<<res;
    return 0;
}