[LeetCode] Length of Last Word

[Problem]
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

.



[Anlysis]

从尾到头遍历，注意NULL指针和后导空格的过滤。

[Solution]

class Solution {
public:
int lengthOfLastWord(const char *s) {
// Start typing your C/C++ solution below
// DO NOT write int main() function

// empty character
if(s == NULL)return 0;

// non-empty character
int len = strlen(s);
int i = len - 1, j = 0;

// filter ending spaces
while(i >= 0 && s[i] == ' '){
i--;
}

// scan the last word
while(i >= 0 && s[i] != ' '){
j++;
i--;
}
return j;
}
};

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