Question

public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str = "Let's take LeetCode contest";
        reverseWords(str);
    }

    private static void reverseWords(String str) {
        // TODO Auto-generated method stub
        String[] words = str.split("\\s");
        String reverse = "";
        String word="";
        ArrayList<String> al = new ArrayList<String>();
        for(int i=0 ; i < words.length;i++){
            al.add(words[i]);
            for(int j=al.get(i).length()-1;j>=0;j--){
                reverse=reverse+al.get(i).charAt(j);
                word= reverse.replaceAll("..", "$0 ");
            }
        }
        System.out.println(str);
        System.out.println(word);
    }

此代码放弃了：“s'teLekatedoCteeLtsetnoc”

但预期的结果应该是：“s'teL ekat edoCteeL tsetnoc”

Answer 1

实际上，发布的代码不会产生您声明的输出;它输出"s' te Le ka te do Ct ee Lt se tn oc"。你是（出于某种原因）一次颠倒一对字母。

有时，最好的方法是尽可能简单地编写代码。以下是如何在一个（IMHO可读）行中执行此操作：

private static void reverseWords(String str) {
    System.out.println(
        Arrays.stream(str.split(" "))       // split into words
        .map(StringBuilder::new)            // use a StringBuilder for each word
        .map(StringBuilder::reverse)        // reverse each word
        .collect(Collectors.joining(" "))); // join em back up with spaces
}

Answer 2

private static void reverseWords(String str) {
    // TODO Auto-generated method stub
    String[] words = str.split("\\s");
    String reverse = "";
    int len = words.length;

    for(int i=0;i<len;i++){
        reverse = reverse+new StringBuilder(words[i]).reverse().toString();
        if(i<len-1){
            reverse = reverse+" ";
        }
    }

    System.out.println(str);
    System.out.println(reverse);
}

尝试将此作为你的reverseWords（）方法。

Answer 3

public class Reverse {

    public static void main(String[] args) {
        String str = "Let's take LeetCode contest";
        reverseWords(str);
    }

    private static void reverseWords(String str) {
        char[] charArray = str.toCharArray();
        boolean flag = false;
        int start = 0;
        int end = 0;
        for (int i = 0; i < str.length(); i++) {
            if (charArray[i] == ' ' && !flag) {
                flag = true;
                end = i - 1;
                reverseWord(charArray, start, end);
            }
            if (charArray[i] != ' ' && flag) {
                start = i;
                flag = false;
            }
        }
        reverseWord(charArray, start, charArray.length - 1);
        System.out.println(str);
        System.out.println(String.valueOf(charArray));
    }

    private static void reverseWord(char[] ch, int i, int j) {
        while (i < j) {
            char temp = ch[i];
            ch[i] = ch[j];
            ch[j] = temp;
            i++;
            j--;
        }
    }
}

如何在翻转单词之后在单词之间打印空格

3 个答案: