LeetCode58-最后一个单词的长度

去除首尾空格,从后遍历

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

先从后跳过空格,然后再从已经去除空格后的index开始计数

public int lengthOfLastWord(String s) {
        int index = s.length() - 1;
        while (s.charAt(index) == ' ') {
            index--;
        }
        int res = 0;
        while (index >= 0 && s.charAt(index) != ' ') {
            res++;
            index--;
        }
        return res;
    }