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
https://leetcode.com/problems/evaluate-reverse-polish-notation/
逆波兰表达式，也就是后缀表达式，做过两道更难的题之后，这题秒了。
http://www.cnblogs.com/Liok3187/p/4564877.html
http://www.cnblogs.com/Liok3187/p/4593365.html
1 /** 2 * @param {string[]} tokens 3 * @return {number} 4 */ 5 var evalRPN = function(tokens) { 6 var resStack = []; 7 var opStack = []; 8 var right, left; 9 for(var i = 0; i < tokens.length; i++){ 10 var curr = tokens[i]; 11 if(/^(\+|\-|\/|\*)$/.test(curr)){ 12 right = resStack.pop(); 13 left = resStack.pop(); 14 if(curr === ‘+‘){ 15 resStack.push(left + right); 16 }else if(curr === ‘-‘){ 17 resStack.push(left - right); 18 }else if(curr === ‘/‘){ 19 resStack.push(parseInt(left / right)); 20 }else if(curr === ‘*‘){ 21 resStack.push(left * right); 22 } 23 }else{ 24 resStack.push(parseInt(curr)); 25 } 26 } 27 return resStack[0]; 28 };
[LeetCode][JavaScript]Evaluate Reverse Polish Notation
原文：http://www.cnblogs.com/Liok3187/p/4619981.html