Leetcode length of last word

Question: a string containing only uppercase and lowercase letters and spaces. Returns the length of the last word. "ABC a" is 1 "ABC" is 3

There are two ideas: one from the beginning and the other from the back.

1. Remember the length of a word before the space from the beginning to the end. If there is a space to the end, output the record value. If there is a word after the space, count it again. Use flag to record whether spaces are encountered.

class Solution {public:    int lengthOfLastWord(const char *s)     {        int flag = 0, cnt = 0;        while(*s != ‘\0‘)        {            if (flag) {cnt = 0; flag = 0;}            while (*s != ‘\0‘ && *s != ‘ ‘) {cnt++;s++;}            while (*s != ‘\0‘ && *s == ‘ ‘) {s++;flag = 1;}        }        return cnt;    }};

2. From the back to the front, first determine the last pointer, and then return the result after hitting the space after the first word.

class Solution {public:    int lengthOfLastWord(const char *s)     {        const char *p = s + strlen(s) - 1;        int cnt = strlen(s), t = 0;        while(cnt > 0)        {            if (*p == ‘ ‘) {p--; cnt--;continue;}            if (cnt > 0 && *p != ‘ ‘)            {                while(cnt > 0 && *p != ‘ ‘)                {                    t++;cnt--;p--;                }                return t;            }        }        return 0;    }};

 

Leetcode length of last word