面试 42-1:翻转单词顺序

一. 题目

输入一个英文句子,翻转句子中单词的顺序,但单词内字符的顺序不变.为简单起见,标点符号和普通字母一样处理.例如输入字符串”I am a student.”,则输出”student. a am I”.

代码请到我的代码库中下载 Point2Offer

二. 代码

package ween_2;/** * 剑指offer: 翻转单词顺序 * 方法:两次翻转,第一次翻转整个句子,第二次翻转单词 * 测试用例:功能测试(有多个单词,1个单词) * 特殊输入测试(空指针,字符串为空,字符串只有空格) * @author dingding * Date:2017-6-20 20:00 * Declaration: All Rights Reserved! */public class ReverseWord {    public static void main(String[] args) {        test1();        test2();        test3();        test4();        test5();    }    //翻转函数    private static void reverse(char[] str,int start,int end){        if (str==null || start<0 || end >str.length ||end <start || str.length<1) {            return;   //if外面的其他语句都不会执行        }        while (start<end){            char tmp = str[start];            str[start] = str[end];            str[end] = tmp;            start++;            end--;        }    }    //翻转句子    private static char[] reverseSentence(char[] str){        if (str == null || str.length<1) {            return str;        }        reverse(str, 0, str.length-1);        int start = 0;        int end = 0;        while (start <str.length ) {            if (str[start] == ' ') {                start++;                end++;            }else if (end == str.length ||str[end] == ' ' ) {  //或的左右顺序有关                reverse(str, start, end-1);                end++;                start = end;            }else {                end++;            }        }        return str;    }    /*====================测试用例=================*/    private static void test1() {        System.out.println(new String(reverseSentence("I am a student.".toCharArray())));    }    private static void test2() {        System.out.println(new String(reverseSentence("Wonderful".toCharArray())));    }    private static void test3() {        System.out.println(new String(reverseSentence("".toCharArray())));    }    private static void test4() {         System.out.println(new String(reverseSentence("    ".toCharArray())));    }    private static void test5() {        if (reverseSentence(null)==null) {            System.out.println("空指针!");        }    }}

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有不妥当之处,麻烦告知:D