LeetCode刷题笔录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

.

这题可以从尾部开始往前扫描，把尾部所有的空格都跳过去，遇到的第一个非空格字符设为end。再从end开始往前扫描，遇到的第一个空格设为start。长度就是end - start。

public class Solution {
public int lengthOfLastWord(String s) {
int end = s.length() - 1;
//search from the end, find the first non-space char
while(end >= 0 && s.charAt(end) == ' ')
end--;
if(end == -1)
return 0;

int start = end;

while(start >= 0 && s.charAt(start) != ' ')
start--;
return end - start;
}
}