No.58 Length of Last Word

No.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.

思路：从后向前遍历字符串，先过滤掉空格，直到遇到空格停止。

class Solution
{
public:
    int lengthOfLastWord(string s)
    {//返回s中最后一个单词的长度
        if(s.size() == 0)
            return 0;

        int end = s.size()-1;
        while(end >=0 && s[end] == ' ')
            end--;//过滤掉后面的空格符
        int i=end;
        while(i>=0)
        {//从后向前遍历
            if(s[i] == ' ')
                break;
            i--;
        }

        return end-i;
    }
};
int main()
{
    Solution sol;
    string test[] = {"Hello world","Hello world   ","","  "};
    
    for(auto const &i : test)
        cout << sol.lengthOfLastWord(i)<<endl;
    return 0;
}