058.Length of Last Word

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Test cases

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""
"Hello World"
"OneWord"
"Space "
" Space"
"b   a    "

Solution 1: accepted 5ms

Time: O(n)
Space: O(1) 

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public int lengthOfLastWord(String s) {
    s = s.trim();
    int len = s.length();
    for(int i = len - 1; i >= 0; i--) {
        if (s.charAt(i) == ' ') {
            return len - i- 1;
            // return s.substring(i + 1, len).length();  // improved
        }
    }
    return len == 0? 0 : len;
}

Other solutions

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public int lengthOfLastWord(String s) {
    return s.trim().length()-s.trim().lastIndexOf(" ")-1;
}
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public class Solution {
    public int lengthOfLastWord(String s) {
        String s1 = s.trim();
        int count = 0;
        for(int i = s1.length() - 1; i >=0; i--){
            if (s1.charAt(i) != ' '){
                count ++;
            }
            else{
                break;
            }
        }
        
       return count; 
    }
}