# Problem 58: Length of Last Word

> <https://leetcode.com/problems/length-of-last-word/>

## 思路

* 从后往前慢慢走

```java
public class Solution {
    public int lengthOfLastWord(String s) {
        if (s == null || s.length() == 0) {
            return 0;
        }  

        int len = s.length(), j = len - 1;
        while (j >= 0 && s.charAt(j) == ' ') j--;

        if (j < 0) {
            return 0;
        }
        int count = 0;
        while (j >= 0 && s.charAt(j) != ' ') {
            count++;
            j--;
        }

        return count;
    }
}
```

## 易错点

1. 注意 space 要留出 space

   ```java
   s.charAt(j) == ' '
   ```

   这里不能写成

   ```java
   s.charAt(j) == ''
   ```

   否则，charAt没法对应一个位置了。