leetcode 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 (last word means the last appearing word if we loop from left to right) in the string.

If the last word does not exist, return 0.

Note: A word is defined as a maximal substring consisting of non-space characters only.

Example:

Input: “Hello World”
Output: 5

• 思路：先去掉末尾的空格，然后从后往前找，到第一个空格的时候停下。很水的题

class Solution {
public:
    int lengthOfLastWord(string s) {
        int res=0;
        int len=s.length();
        int i=len-1;
        while(i>=0&&s[i]==' ')i--;
        for(;i>=0;i--){
            if(s[i]==' ')break;
            else res++;
        }
        return res;
    }
};