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  1. #include <iostream>
  2. #include <stack>
  3. #include <string>
  4. using namespace std;
  5.  
  6. int main() {
  7.     int t;
  8.     cin >> t;
  9.  
  10.     while (t--) {
  11.         string expr;
  12.         cin >> expr;
  13.  
  14.         stack<long long> st;
  15.         bool valid = true;
  16.  
  17.         for (int i = expr.size() - 1; i >= 0; --i) {
  18.             char c = expr[i];
  19.             if (c >= '0' && c <= '9') {
  20.                 st.push(c - '0');  // convert char to number
  21.             } else if (c == '+' || c == '-' || c == '*' || c == '/') {
  22.                 if (st.size() < 2) {
  23.                     valid = false;
  24.                     break;
  25.                 }
  26.                 long long a = st.top(); st.pop();
  27.                 long long b = st.top(); st.pop();
  28.                 if (c == '+') st.push(a + b);
  29.                 else if (c == '-') st.push(a - b);
  30.                 else if (c == '*') st.push(a * b);
  31.                 else if (c == '/') {
  32.                     if (b == 0) {
  33.                         valid = false;
  34.                         break;
  35.                     }
  36.                     st.push(a / b);
  37.                 }
  38.             } else {
  39.                 valid = false;
  40.                 break;
  41.             }
  42.         }
  43.  
  44.         if (valid && st.size() == 1) {
  45.             cout << st.top() << endl;
  46.         } 
  47.  
  48.     }
  49.  
  50.     return 0;
  51. }
Success #stdin #stdout 0.01s 5324KB
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https://ideone.com/J91EQw
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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