[LeetCode] Length of Last Word

Posted 2020-10-14 immjc

 

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

找出字符串中最后一个单词的长度。

利用istringstream来去除字符串中的空格，保存最后一个单词并返回它的长度即可。

class Solution {
public:
    int lengthOfLastWord(string s) {
        string word;
        istringstream in(s);
        while (in >> word) {}
        return word.size();
    }
};
// 6 ms

使用遍历判断空格。

如果最后一位非‘ ’，则累计字母，如果如要空格并且计数非0跳出循环。

class Solution {
public:
    int lengthOfLastWord(string s) {
        int len = 0;
        for (int i = s.size() - 1; i >= 0; i--) {
            if (s[i] == ‘ ‘) {
                if (len != 0)
                    break;
            }
            else
                len++;
        }
        return len;
    }
};
// 6 ms