首页 > 代码库 > Evaluate Reverse Polish Notation
Evaluate Reverse Polish Notation
Evaluate the value of an arithmetic expression in Reverse Polish Notation.
Valid operators are +
, -
, *
, /
. Each operand may be an integer or another expression.
Some examples:
["2", "1", "+", "3", "*"] -> ((2 + 1) * 3) -> 9 ["4", "13", "5", "/", "+"] -> (4 + (13 / 5)) -> 6
class Solution {public: int evalRPN(vector<string> &tokens) { stack<int> nums; int num = tokens.size(); int i=0; if(num == 1) return tonum(tokens[0]); while(i<num){ while(i<num && !isop(tokens[i])){ int tmp = tonum(tokens[i]); nums.push(tmp); i++; } int op2 = nums.top(); nums.pop(); int op1 = nums.top(); nums.pop(); if(tokens[i] == "+"){ nums.push(op1+op2); } else if(tokens[i] == "*"){ nums.push(op1 * op2); } else if(tokens[i] == "-"){ nums.push(op1 - op2); } else if(tokens[i] == "/"){ nums.push(op1 / op2); } i++; } return nums.top(); } int tonum(string s){ int num; stringstream ss(s); ss >> num; return num; } bool isop(string str){ if(str.length() > 1) return false; if(str == "+") return true; if(str == "*") return true; if(str == "-") return true; if(str == "/") return true; }};
Evaluate Reverse Polish Notation
声明:以上内容来自用户投稿及互联网公开渠道收集整理发布,本网站不拥有所有权,未作人工编辑处理,也不承担相关法律责任,若内容有误或涉及侵权可进行投诉: 投诉/举报 工作人员会在5个工作日内联系你,一经查实,本站将立刻删除涉嫌侵权内容。