58. Length of Last Word

Given a string s consists of some words separated by spaces, return the length of the last word in the string. If the last word does not exist, return 0.

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

Example 1:

Input: s = "Hello World"
Output: 5

Example 2:

Input: s = " "
Output: 0

class Solution {
public:
    int lengthOfLastWord(string s) {
        
        //String last = "";
        
        if(s == " "){
            return 0;
        }
        
        int len = 0;
        int prev = 0;
        
        for(int i=0; i<s.length(); i++){
            if(s[i] == ' '){
                len = 0;
                continue;
            }
            else{
                len++;
            }
            
            if(len != 0){
                prev = len;
            }
}
        
        return (len==0)? prev:len;
    }
};

TIPS:

corner case:

1. “ “ -> 0
2. “a “ -> 1 : to solve this corner case, I use variable prev to store the previous value of len.

Runtime: 4 ms, faster than 64.17% of C++ online submissions for Length of Last Word.

Memory Usage: 6.5 MB, less than 59.45% of C++ online submissions for Length of Last Word.