Java program to determine the array is a subset of another array

October 12, 2022

Array is a subset of another array in Java

In this section we will determine the program to find if an Array is a subset of another array in Java which is discussed here. If all the elements of array 2 are found in array 1, then array 2 is said to be a subset of array 1.

Example

arr1 = {1,2,3,4,5} , arr2 = {3,4,5}
arr2 is a subset of arr1 (As, arr1 contains all the elements of arr2)
arr3 = {1,2,3,4,5} arr4 = {1,2,9}
arr4 is not a subset of arr3 (As, arr3 do not contains all the elements of arr4).

Method Discussed :

Method 1 : Using nested loops
Method 2 : Using sorting and binary search.
Method 3 : Using sorting and merging.
Method 4 : Using Hashing

Method 1 :

Run a loop for loo from index 0 to length of arr2
Run a inner loop from index 0 to length of arr2
If(arr2[i]==arr1[j]), then break the inner loop
Check if(j==m) then return 0.
Otherwise, return 1.

Method 1 : Code in Java

class Main{

   static boolean isSubset(int arr1[], int arr2[], int m, int n)
    {
        int i = 0;
        int j = 0;
        for (i = 0; i < n; i++) {
            for (j = 0; j < m; j++) {
                if (arr2[i] == arr1[j])
                    break;
            }
 
            if (j == m)
            return false;
        }
 
        return true;
    }
 
    public static void main(String args[])
    {
        int arr1[] = { 11, 10, 13, 21, 30, 70 };
        int arr2[] = { 11, 30, 70, 10 };
    
        int m = arr1.length;
        int n = arr2.length;
 
        if (isSubset(arr1, arr2, m, n))
            System.out.print("arr2[] is subset of arr1[] ");
        else
            System.out.print("arr2[] is not subset of arr1[] ");
 
    }
}

Output :

arr2[] is subset of arr1[]

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Method 2 :

In this method we first sort arr1 then, using binary search we find the elements of arr2 in arr1

Sort arr1[] using inbuilt sort function.
For each element of arr2[], do binary search for it in sorted arr1[].
If the element is not found then return 0.
If all elements are present then return 1.

Method 2 : Code in Java

import java.util.Arrays;
class Main{

   static boolean isSubset(int arr1[], int arr2[], int m, int n)
    {
        int i = 0;
 
        for (i = 0; i < n; i++) {
            if (binarySearch(arr1, 0, m - 1, arr2[i]) == -1)
                return false;
        }
 
        return true;
    }
 
    static int binarySearch(int arr[], int low, int high, int x)
    {
        if (high >= low)
        {
            /*low + (high - low)/2;*/
            int mid = (low + high)/ 2;
 
            if ((mid == 0 || x > arr[mid - 1])&& (arr[mid] == x))
                return mid;
            else if (x > arr[mid])
                return binarySearch(arr,(mid + 1), high,x);
            else
                return binarySearch(arr, low,(mid - 1), x);
        }
        return -1;
    }
    public static void main(String args[])
    {
        int arr1[] = { 11, 10, 13, 21, 30, 70 };
        int arr2[] = { 11, 30, 70, 10 };
    
        int m = arr1.length;
        int n = arr2.length;
        
        Arrays.sort(arr1);
 
        if (isSubset(arr1, arr2, m, n))
            System.out.print("arr2[] is subset of arr1[] ");
        else
            System.out.print("arr2[] is not subset of arr1[] ");
 
    }
}

Output :

arr2[] is subset of arr1[]

Method 3 :

Sort both arrays: arr1[] and arr2[] using inbuilt sort function.
Use Merging process to see if all elements of sorted arr2[] are present in sorted arr1[].

Method 3 : Code in Java

import java.util.Arrays;
class Main{

   static boolean isSubset(int arr1[], int arr2[], int m, int n)
    {
        int i = 0, j = 0;
 
        if (m < n)
            return false;
 
        Arrays.sort(arr1); // sorts arr1
        Arrays.sort(arr2); // sorts arr2
 
        while (i < n && j < m) {
            if (arr1[j] < arr2[i])
                j++;
            else if (arr1[j] == arr2[i]) {
                j++;
                i++;
            }
            else if (arr1[j] > arr2[i])
                return false;
        }
 
        if (i < n)
            return false;
        else
            return true;
    }
 
    
    public static void main(String args[])
    {
        int arr1[] = { 11, 10, 13, 21, 30, 70 };
        int arr2[] = { 11, 30, 70, 10 };
    
        int m = arr1.length;
        int n = arr2.length;
        
        if (isSubset(arr1, arr2, m, n))
            System.out.print("arr2[] is subset of arr1[] ");
        else
            System.out.print("arr2[] is not subset of arr1[] ");
 
    }
}

Output :

arr2[] is subset of arr1[]

Method 4 :

In this method we will use the concept of hashing.

Method 4 : Code in Java

import java.util.Arrays;
import java.util.HashSet;
class Main{

   static boolean isSubset(int arr1[], int arr2[], int m, int n)
    {
        HashSet set = new HashSet<>();
 
        for (int i = 0; i < m; i++) {
            if (!set.contains(arr1[i]))
                set.add(arr1[i]);
        }
 
        
        for (int i = 0; i < n; i++)
        {
            if (!set.contains(arr2[i]))
                return false;
        }
        return true;
    }
 
    
    public static void main(String args[])
    {
        int arr1[] = { 11, 10, 13, 21, 30, 70 };
        int arr2[] = { 11, 30, 70, 10 };
    
        int m = arr1.length;
        int n = arr2.length;
        
        if (isSubset(arr1, arr2, m, n))
            System.out.print("arr2[] is subset of arr1[] ");
        else
            System.out.print("arr2[] is not subset of arr1[] ");
 
    }
}

Output :

arr2[] is subset of arr1[]

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7 comments on “Java program to determine the array is a subset of another array”

Lakhan Rathore
// Determine Array is a subset of another array or not :

class Lakhan
{
public static void main(String ar[])
{
int x[]={1,3,5,7,8,9};
int y[]={1,3,5,7};
int n=x.length;
int m=y.length;
int f=0;
for(int i=0;i<n;i++)
{
for(int j=0;j<m;j++)
{
if(x[i]==y[j])
{
f++;
break;
}
}
}
if(m==f)
System.out.println("y is subset of x");
else
System.out.println("y is not subset of x");
}
}

0

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Gyanendra
import java.util.*;
public class Main{
public static void main(String[] args){
Scanner scn=new Scanner(System.in);
int n=scn.nextInt();
int[] arr=new int[n];

for(int i=0;i<n;i++){
arr[i]=scn.nextInt();
}
int n2=scn.nextInt();
int[] arr2=new int[n2];

for(int i=0;i<n2;i++){
arr2[i]=scn.nextInt();
}

if(subset(arr,arr2)==true){
System.out.println("arr2 is a subset of arr1");
}
else{
System.out.println("arr2 is not a subset of arr1");
}
}

public static boolean subset(int[] arr,int[] arr2){

for(int j=0;j<arr2.length;j++){
int count=0;
for(int i=0;i<arr.length;i++){
if(arr[i]==arr2[j])
count++;
}

if(count==0)
return false;
}
return true;
}
}

0

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Gokul
class HelloWorld {

static boolean checksubset(int a1[],int a2[])
{
boolean temp=false;

for(int i=0;i<a2.length;i++)
{
for(int j=0;j<a1.length;j++)
{
if(a2[i]==a1[j])
{
temp=true;
break;
}
}
if(temp)
{
temp=false;
continue;
}
return false;
}

return true;

}

public static void main(String[] args) {

int a1[]={11,1,13,21,3,7};
int a2[]={11,1,21,13};

if(checksubset(a1,a2))
System.out.print("yes");
else
System.out.print("no");

}
}

0

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irshadahmed1308
public static void main(String[] args) {
int arr1[]={3,4,5,2,1};
int arr2[]={1,2,9};
int flag=0;
Arrays.sort(arr1);
Arrays.sort(arr2);

for(int i=0;i< arr2.length;i++)
{
if(arr1[i]==arr2[i])
{
flag++;
}
}
if(flag==arr2.length)
{
System.out.println("arr1 has the subarray with arr2");
}
else
System.out.println("there is no sub-array");

}
}

0

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sandesh
import java.util.Scanner;

public class arrayIsSubsetOfOtherArray {
public static boolean isSubset(int[] array1, int[] array2,int len1,int len2) {
int i,j;

for (i=0; i < len1; i++){
if (array1[i] ==array2[0]){
int count=1;
for (j=1; j < len2; j++){
if (array1[i+j] == array2[j]){
count++;
}
}
System.out.println(count);
if (count ==len2){
return true;
}
}
}
return false;
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int len1=scanner.nextInt();
int len2=scanner.nextInt();
int[] array1=new int[len1];
int[] array2=new int[len2];
for(int i=0; i<len1; i++) {
array1[i] =scanner.nextInt();
}
for(int i=0; i<len2; i++) {
array2[i] =scanner.nextInt();
}
if(isSubset(array1, array2, len1, len2)) {
System.out.println("yes");
}
else {
System.out.println("no");
}
scanner.close();
}

}

0

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Ayushi
#Python Program

arr1 = list(map(int, input(“Enter array 1: “).split()))
arr2 = list(map(int, input(“Enter array 2: “).split()))

count = 0
for i in arr1:
for j in arr2:
if i == j:
count+=1
continue

if count == len(arr2):
print(“{} is a subset of {}”.format(arr2, arr1))
else:
print(“{} is not a subset of {}”.format(arr2, arr1))

0

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Anurag
int[] arr1 = {1,2,3,4,5};
int[] arr2 = {3,4,5};
int subset=0;
for(int i=0;i<arr1.length;i++)
{
for(int j=0;j0)
System.out.println(“true”);
else
System.out.println(“false”);

0

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