LeetCode:Length of Last Word

题目链接

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.

---

 

借助strlen函数，相当于遍历两遍字符串                       本文地址

class Solution {
public:
    int lengthOfLastWord(const char *s) {
        if(s == NULL)return 0;
        int len = strlen(s), i, res = 0;
        for(i = len-1; i >= 0 && s[i] == ' '; i--);//从尾部开始找到第一个非空格字符
        for(; i >= 0 && s[i] != ' '; i--)res++;
        return res;
    }
};

遍历一遍字符串

class Solution {
public:
    int lengthOfLastWord(const char *s) {
        if(s == NULL)return 0;
        int res = 0, cnt = 0;
        for(; *s != '\0'; s++)
        {
            if(*s == ' ')
            {
                if(cnt != 0)
                    res = cnt;
                cnt = 0;
            }
            else cnt++;
        }
        return cnt == 0 ? res : cnt;
    }
};

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