L58: 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.

解题思路：遇到非’ ‘字符，用一个符号表示word開始，遇到’ ‘表示word结束，注意边界情况处理

优化：能够从字符串末尾開始处理

class Solution {public:    int lengthOfLastWord(string s) {        int strLen = s.length();        if(strLen == 0)            return 0;        int begin = 0;        int end = 0;        int pos = 0;        bool word_start = false;        while(pos < strLen)        {            if(s[pos] != ' ' && !word_start)             {                begin = pos;                word_start = true;            }            else if(s[pos] == ' ' && word_start)            {                end = pos;                word_start = false;            }            pos++;        }        if (word_start && pos == strLen)            end = strLen;        return end - begin;    }};