Leetcode - Evaluate Reverse Polish Notation

初看貌似有点复杂，但是搞懂了非常简单，就一个简单的栈应用，每次遇到计算符号"+", "-", "*", "/"就将栈顶端两个数字出栈，计算后再将结果压栈即可。。

#include<iostream>#include<vector>#include<stack>using namespace std;class Solution {public:int evalRPN(vector<string> &tokens) {stack<int> stack;for (int i = 0; i < tokens.size(); i++){if (tokens[i] == "*" || tokens[i] == "-" || tokens[i] == "+" || tokens[i] == "/"){int val2 = stack.top();stack.pop();int val1 = stack.top();stack.pop();int tmpVal;if (tokens[i] == "*")tmpVal = val1 * val2;else if (tokens[i] == "-")tmpVal = val1 - val2;else if (tokens[i] == "+")tmpVal = val1 + val2;elsetmpVal = val1 / val2;stack.push(tmpVal);}else{int tmpVal = atoi(tokens[i].c_str());stack.push(tmpVal);}}return stack.top();}};