【leetcode刷题笔记】Length of Last Word

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.

If the last word does not exist, return 0.

Note: A word is defined as a character sequence consists of non-space characters only.

For example, 
Given s = "Hello World",
return 5.

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题解：简单题，从后往前遍历就可以了。注意边界问题。

代码如下：

public class Solution {
    public int lengthOfLastWord(String s) {
        int answer = 0;
        int i = s.length()-1;
        while(i >= 0 && s.charAt(i) == ' ')
            i--;
        for(;i >= 0;i--){
            if(s.charAt(i) != ' ')
                answer++;
            else {
                break;
            }
        }
       
        return answer;
    }
}

特别要注意第5行while循环时候要判断边界。