题解 | #逆波兰表达式求值#

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param tokens string字符串vector 
     * @return int整型
     */
    int evalRPN(vector<string>& tokens) {
        // write code here
        stack<int> str;
        for (const string& token : tokens) {
            if (token == "+" || token == "-" || token == "*" || token == "/") {
                int right = str.top(); str.pop();
                int left = str.top(); str.pop();
                if (token == "+") str.push(left + right);
                else if (token == "-") str.push(left - right);
                else if (token == "*") str.push(left * right);
                else if (token == "/") str.push(left / right);
            } else {
                str.push(stoi(token));
            }
        }
        return str.top();
    }
};