使用递归反转句子的 Java 程序
原文:https://www . geesforgeks . org/Java-program-to-reverse-a-句子-使用递归/
句子是由一些分隔符分隔的字符序列。这个字符序列从第 0 个索引开始，最后一个索引在 len(string)-1。通过反转字符串，我们从第 0 个索引开始交换字符，并从末尾开始放置它们。第一个字符变成最后一个，第二个变成第二个最后一个，以此类推。
例:
Input : GeeksforGeeks
Output: skeegrofskeeG
Input : Alice
Output: ecilA
方法:
- Check whether the string is empty or not, and return null if it is empty.
- If the string is empty, an empty string is returned.
- Otherwise, the connection between the substring part of the string from index 1 to the length of the string and the first character of the string is returned. E.g. return substring (1)+str.charat (0); That is, the return of the string "Mayur" will be "ayur"+"m".
下面是上述方法的实现:
T3】JavaT5
// Java Program to Reverse a Sentence Using Recursion
import java.io.*;
public class GFG {
public static String reverse_sentence(String str)
{
// check if str is empty
if (str.isEmpty())
// return the string
return str;
else {
// extract the character at 0th index, that is
// the character at beginning
char ch = str.charAt(0);
// append character extracted at the end
// and pass the remaining string to the function
return reverse_sentence(str.substring(1)) + ch;
}
}
public static void main(String[] args)
{
// specify the string to reverse
String str = "Geeksforgeeks";
// call the method to reverse sentence
String rev_str = reverse_sentence(str);
// print the reversed sentence
System.out.println(
"Sentence in reversed form is : " + rev_str);
// creating another string with numbers
// and special characters
String str2 = "Alice";
String rev_str2 = reverse_sentence(str2);
// print the reversed sentence
System.out.println(
"Sentence in reversed form is : " + rev_str2);
}
}
T6T8输出T1
时间复杂度: O(N)，其中 N 为字符串的长度。
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