LeetCode_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.

　　方法一： 正面扫描

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

        int len  = strlen(s);
        if(len == ) return ;
        char temp[];
        int result =;
        int pos = ;
        while(pos < len)
        {
           while(pos < len && s[pos]== ' ') pos++;

          int num = sscanf(s + pos, "%s", temp);
          if(num == -) break;
          result = strlen(temp);
          pos = pos + result;

        }

      return result;
    }
};

方法二：反向扫描

class Solution {
public:
    int lengthOfLastWord(const char *s) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int len =strlen(s) ;
        int i = len -;
        while(i>= && s[i] == ' ') i--;
        if(i == -) return  ;

        int count  = ;
        while(i>= && s[i]!= ' ')
        {
          count++;
          i--;
        }

        return count ;

    }
};