Length of Last Word

描述

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.

分析

模拟。先从右到左找到第一个字母，然后从右到左找到第一个非字母，二者的距离就是最后一个word的长度。

代码

// Length of Last Word
// 偷懒，用 STL
// 时间复杂度O(n)，空间复杂度O(1)
class Solution {
public:
    int lengthOfLastWord(const string& s) {
        auto first = find_if(s.rbegin(), s.rend(), ::isalpha);
        auto last = find_if_not(first, s.rend(), ::isalpha);
        return distance(first, last);
    }
};