题解 | #翻转单词序列#

import java.util.*;
public class Solution {
    public String ReverseSentence(String str) {
        String ret = "";

        int tail = str.length()-1;
        for (int i = str.length()-1; i >= 0; i--){
            if (i == 0 || str.charAt(i) == ' '){
                int j = (i == 0) ? 0 : i + 1;
                while(j <= tail){
                    ret += str.charAt(j);
                    j++;
                }

                if (i != 0){
                    ret += " ";
                    while(str.charAt(i) == ' '){
                        i--;
                    }
                    tail = i;
                    if (i == 0){
                        i++;
                    }
                }
                
                
            }
        }

        return ret;
    }
}