Leetcode58. Length of the last word

Title transmission address : https://leetcode.cn/problems/length-of-last-word/

Operational efficiency :

The code is as follows :

public static int lengthOfLastWord(String s) {
    
        // Dealing with boundary conditions 
        if ("".equals(s.trim())) {
      // about " " This need trim()
            return 0;
        }
        if (s.length() == 1) {
    
            return 1;
        }
        int lastWordEnd = s.length() - 1;
        // Find the end of the last word first 
        while (lastWordEnd != -1 && s.charAt(lastWordEnd) == ' ') {
    
            lastWordEnd--;
        }
        int lastWordStart = lastWordEnd;
        // Find the first letter of the last word 
        while (lastWordStart!=-1&&s.charAt(lastWordStart) != ' ') {
    
            lastWordStart--;
        }
        // because subtsring(start,end) The string intercepted by the function does not contain end The character of position , So next +1
        String substring = s.substring(lastWordStart + 1, lastWordEnd + 1);
        return substring.length();
    }