Length of Last Word, Leetcode 解题笔记

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.

这题思路很简单,就是从后往前找空格,但是要注意考虑到所有的情况。比如我一开始就没想到“a ”这种以空格为结尾的情况。

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