151. Reverse Words in a String

str.trim.split(" +") 然后用StringBuilder
https://leetcode.com/problems/reverse-words-in-a-string/discuss/161008/6-line-Java-answer

 

//Old
class Solution {
    public String reverseWords(String s) {
        if(s.length() == 0) return s;
        char[] arr = s.toCharArray();
        List<String> list = new ArrayList<>();
        for(int i = 0; i < arr.length; i++) {
            String str = "";
            while( i < arr.length && arr[i] != ' ') {
                str += arr[i];
                i++;
            }
            if(str.length() != 0) {
                list.add(new String(str));
            }
        }
        String res = "";
        for(int i = list.size() - 1; i >= 0; i--) {
            res += list.get(i);
            if(i != 0) res += " ";
        }
        return res;
        
    }
}