58. 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.

从字符串的末尾往前遍历。

首先跳过空格。

然后对第一个连续非空格字符串中的字符个数计数。

class Solution {public:    int lengthOfLastWord(string s) {                int i = s.length()-1;        int len = 0;        while(i>=0 && s[i] == ' ')            --i;        while(i>=0 && s[i] != ' ')        {            ++len;            --i;        }                return len;                    }};

class Solution {public:    int lengthOfLastWord(string s) {                int retLen = 0;        for(int i = 0;i< s.length();i++)        {            while(s[i] == ' ')                i++;            int curLen = 0;            while(s[i] != ' ' && s[i] != '\0')            {                curLen++;                i++;            }            if(curLen != 0)                retLen = curLen;        }        return retLen;                    }};