leetcode 227: Basic Calculator II

Basic Calculator II

Implement a basic calculator to evaluate a simple expression string.

The expression string contains only non-negative integers, +, -, *, / operators and empty spaces . The integer division should truncate toward zero.

You may assume that the given expression is always valid.

Some examples:

"3+2*2" = 7
" 3/2 " = 1
" 3+5 / 2 " = 5

Note: Do not use the eval built-in library function.

[思路]

pass兩遍, 第一遍, 先解決乘除, 第二遍, 做加減.

[CODE]

public class Solution {
    public int calculate(String s) {
        if(s==null || s.length()==0) return 0;
        
        LinkedList list = new LinkedList();
        
        for(int i=0; i