CareerCup

Save the integers as a HashMap where key is the integer and value is the number of occurences. Then following program solves it.

package epic_passwords;

import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Set;

public class Passwords {
	private static HashMap<Integer,Integer> password = new HashMap<Integer,Integer>();
	private static LinkedList<Integer> oneCombination = new LinkedList<Integer>();
	
	public static void main(String[] args){
		password.put(1, 1);
		password.put(9, 3);
		password.put(4, 2);
		findCombi(password, oneCombination);
	}
	
	private static void findCombi(HashMap<Integer,Integer> password, LinkedList<Integer> oneCombination){
		Set<Integer> keys = password.keySet();
		Iterator<Integer> keysItr = keys.iterator();
		//Integer keyRemoved = null;
		Integer value;
		while(keysItr.hasNext()){
			Integer key = keysItr.next();
			if(password.get(key)==0){
				continue;
			}else{
				value = password.get(key);
				value--;
				password.put(key, value);
			}
			oneCombination.add(key);
			showPassword(oneCombination);
			findCombi(password, oneCombination);
			oneCombination.removeLast();
			value++;
			password.put(key, value);
		}
	}
	
	private static void showPassword(LinkedList<Integer> oneCombination){
		int size = oneCombination.size();
		System.out.println("\n");
		for(int i=0; i<size; i++){
			System.out.print(oneCombination.get(i));
		}
	}
	
}

public class Combination {


public static void main(String[] args) {
permutation("", "123");
}


private static void permutation(String prefix, String str) {

int n = str.length();

if(n ==0)
System.out.println(prefix);
else {
for(int i = 0; i<n ;i++){
permutation(prefix+str.charAt(i), str.substring(0,i)+str.substring(i+1));
}

}
}
}

public class Combination {


public static void main(String[] args) {
permutation("", "123");
}


private static void permutation(String prefix, String str) {

int n = str.length();

if(n ==0)
System.out.println(prefix);
else {
for(int i = 0; i<n ;i++){
permutation(prefix+str.charAt(i), str.substring(0,i)+str.substring(i+1));
}
}
}
}

#include<iostream>
#include<algorithm>
#include<string.h>
using namespace std;
int main()
{
char st[]="231";
int len=strlen(st);
sort(st,st+len);
do
{
cout<<st<<endl;
}while(next_permutation(st,st+len));
return 0;
}

public static void main(String args[]) {
permuteString("", "123");
}

public static void permuteString(String beginningString, String endingString) {
if (endingString.length() <= 1)
System.out.println(beginningString + endingString);
else
for (int i = 0; i < endingString.length(); i++) {
try {
// System.out.println(i);
String newString = endingString.substring(0, i) + endingString.substring(i + 1);
permuteString(beginningString + endingString.charAt(i), newString);
} catch (StringIndexOutOfBoundsException exception) {
exception.printStackTrace();
}
}
}

public static void main(String args[]) {
permuteString("", "123");
}

public static void permuteString(String beginningString, String endingString) {
if (endingString.length() <= 1)
System.out.println(beginningString + endingString);
else
for (int i = 0; i < endingString.length(); i++) {
try {
// System.out.println(i);
String newString = endingString.substring(0, i) + endingString.substring(i + 1);
permuteString(beginningString + endingString.charAt(i), newString);
} catch (StringIndexOutOfBoundsException exception) {
exception.printStackTrace();
}
}
}