Reverse Words in a String

leetcode:https://oj.leetcode.com/problems/reverse-words-in-a-string

今天写了开题报告，有点不太想开那个报告了，没事又去A了一道ACM。这次A的是系统随机推荐的，刚看的时候以为是一个Easy类型的。感觉不太难

PS:一开始把题目理解错了，以为直接把所有字符Reverse。实际是将单词Reverse，单词里面的不用Reverse。

 

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

For example,
Given s = "the sky is blue",
return "blue is sky the".

public class Solution_Reserse {
    public String reverseWords(String str){
        String str_result = "";
        String str_word = "";
        char array_src[] = str.toCharArray();
        char array_word[];
        int count = 0;
        int i =array_src.length - 1;
        int j = i;
        boolean isWord = false;        //判断是否有单词
        
        while(j >= 0){
            while(j >= 0 && array_src[j] != ' '){
                count++;
                j--;
            }//找出单词长度
            array_word = new char[count];//存放单词数组

            while(i >= 0 && array_src[i] != ' '){
                count--;
                array_word[count] = array_src[i];                
                i--;
                isWord = true;
            }//单词已按正确顺序放好
            if(isWord){
                str_word = new String(array_word);//一个单词字符串
                str_result += str_word + " ";//拼接到结果字符串中
            }
            
            isWord = false;
            j--;
            i--;
        }
        if("" == str || " " == str)
            return "";
        else if(str_result.length() != 0)
            str_result = str_result.substring(0, str_result.length() - 1);
        return str_result;
    }
}

 贴个特别简单的实现

public class Solution_Reserse {
    public String reverseWords(String str){
        StringBuilder sb = new StringBuilder();
        String[] split = str.split("\\s+");
        int len = split.length;
        for(int i=len-1; i>=0; i--){
            sb.append(split[i]).append(" ");
        }
        return sb.toString().trim();
    }
}