Reverse Words in a String

题目
Given an input string, reverse the string word by word.

答案

public class Solution {
    public String reverseWords(String s) {
        StringBuilder sb = new StringBuilder();
        // extract word, insert to a string buidler
        int i = 0;
        while(i < s.length()) {
            char c = s.charAt(i);
           if(c != ' ') {
                // find next space, or end of string
               int pos = s.indexOf(' ', i);
                if(pos == -1) pos = s.length();

                String word = s.substring(i, pos);
                sb = sb.insert(0, word + " ");

                i += word.length();
                continue;
           }
            i++;
        }
        return sb.toString().trim();
    }
}