58. Length of Last Word

题目

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.

Example:

Input: "Hello World"
Output: 5

解析

• 主要处理末尾的空格！！

class Solution_58 {
public:

    // 反向查找，末尾空格忽略，行中出现空格就终止循环

    int lengthOfLastWord(string s) {
        int ret = 0;
        if (s.empty())
        {
            return ret;
        }
        int i = s.size() - 1;
        while (i>=0&&s[i] == ' ')
        {
            i--;
        }
            
        for (; i >= 0;i--)
        {   
            if (s[i]==' ')
            {
                break;
            }
            ret++;
        }
        return ret;
    }

    int lengthOfLastWord(const char *s) {

        int ret = 0;
        int len = strlen(s);

        for (int i = len - 1; i >= 0;i--)
        {
            if (s[i]==' ')
            {
                if (ret) //忽略末尾的空格，当遇到空格且有元素时，返回
                {
                    break;
                }
            }
            else
            {
                ret++;
            }
        }
        return ret;
    }
};

题目来源

• 58. Length of Last Word