Length of Last Word

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58.Length of Last Word

Given a string s consisting of words and spaces, return the length of the last word in the string.

A word is a maximal substring consisting of non-space characters only.

Example 1:

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Input: s = "Hello World"
Output: 5
Explanation: The last word is "World" with length 5.

Example 2:

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Input: s = "   fly me   to   the moon  "
Output: 4
Explanation: The last word is "moon" with length 4.

Example 3:

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Input: s = "luffy is still joyboy"
Output: 6
Explanation: The last word is "joyboy" with length 6.

个人解答：

时间复杂度：O(n)

空间复杂度：O(1)

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int lengthOfLastWord(string s) {
    int s_size = s.size();
    int count = 0;
    for (int i = s_size; i >= 0; --i) {
        if (isalpha(s[i]))
            count++;
        else {
            if (count > 0)
                return count;
        }
    }
    return count;//单词前不存在空格的情况
}