题解 | 后缀序列求值

#include<iostream>
#include<stack>

using namespace std;

int main() {
    string s;
    cin >> s;
    stack<int> stack;
    for (char c : s) {
        if (isdigit(c)) stack.push(c - '0');
        else {
            int b = stack.top();
            stack.pop();
            int a = stack.top();
            stack.pop();
            switch (c) {
                case '+':
                    stack.push(a + b);
                    break;
                case '-':
                    stack.push(a - b);
                    break;
                case '*':
                    stack.push(a * b);
                    break;
                case '/':
                    stack.push(a / b);
                    break;
            }
        }
    }
    cout << stack.top();
    return 0;
}