11. Permutations of a given string

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11. Permutations of a given string


Problem link :- click here


package programs;

import java.util.ArrayList;
import java.util.List;

public class String__11
{
	/*
	 	Given a string S. The task is to  print all permutations of a given string.
	 				s = "abc"
	 			output : abc, acb, bac, bca, cab, cba
	 	
	 */
	
	static void permutation(String str, int l, int r)
	{
		if(l==r)
			System.out.print(str + "\t");
		else
		{
			for(int i=l; i<=r; i++)
			{
				str = swap(str, l, i);
				permutation(str, l+1, r);
				str = swap(str, l, i);
			}
		}
	}
	
	static String swap(String str, int i, int j)
	{
		char st[] = str.toCharArray();
		char temp = st[i];
		st[i] = st[j];
		st[j] = temp;
		
		String s = String.valueOf(st);
		return s;
	}

	public static void main(String[] args)
	{
		String s = "abc";
		permutation(s, 0, s.length()-1);
	}

}

Time complexity :- O(n!*n)
Space complexity :- O(n)

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