[leetcode]58. Length of Last Word最后一个词的长度

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.

Example:

Input: "Hello World"
Output: 5

题意：

最后一个词的长度

Solution1： Just like do the simulation of  s.trim().

code

 /*
 Time: O(n).
 Space: O(1).
 */
 class Solution {
      public int lengthOfLastWord(String s) {
         // corner case
         if (s == null || s.length() == 0) return 0;
         int right = s.length() - 1;
         int i = 0;
         // 先把last word右边的空格扫清
         while (right > 0 && s.charAt(right) == ' ') right--;
         i = right;
         // 定住right, 用i来扫出last word的长度
         while (i >= 0 && s.charAt(i) != ' ') i--;
         return right - i;
     }
 }