Length of the last word

Oct 22, 2020#算法 #C #leetcode31

AI Translation

This post is translated from Chinese into English through AI.View Original

AI-generated summary

Given a string containing only lowercase and uppercase letters and spaces, return the length of the last word. If there is no last word, return 0. A word is defined as a string consisting of letters without any spaces. The function should first check for an empty string and then search for the last word by counting the characters from the last non-space element. It should be careful to avoid going out of bounds when searching for the last word.

Description#

Given a string s consisting of only letters and spaces ' ', return the length of the last word.

If the last word does not exist, return 0.

Note: A word is defined as a sequence of non-space characters.

Example:

Input: "Hello World"
Output: 5

Approach#

Return 0 for an empty string
Search for the last non-space character in reverse order, return 0 if not found
Count from the non-space character until a space is encountered or the search ends, return the count

int lengthOfLastWord(char * s){
    int length = strlen(s) - 1, word_length = 0;

    if(length < 0)//empty string
        return 0;
    
    while (s[length] == ' ')//find the last non-space character
        if(--length < 0)//check if search is complete
            return 0;
    
    for(;length >= 0 && s[length] != ' '; length--)//character is non-space and search is not complete
        word_length++;

    return word_length;
}

Note#

When searching for the last non-space character, it is important to check for a space first, then decrement the length, and finally check if the search is complete to avoid out-of-bounds issues