Finding if Arrays are disjoint or not using C++

October 12, 2022

Arrays are Disjoint or not in C++

Here, in this page we will discuss the program to check whether the two arrays are disjoint or not in C++ programming language. Arrays are disjoint if the don’t contain any common value.

Arrays are disjoint or not in C++

Here, we will discuss the following methods to check whether the given integer arrays are disjoint or not

  • Method 1 : Using Naive approach.
  • Method 2 : Using sorting and hashing
  • Method 3 : Using Set

Method 1 :

  • Run a loop from index 0 to n
  • Run a nested loop from 0 to m
  • Check if (arr1[i]==arr2[j]) return 0.
  • Otherwise, return 1.

Time and Space Complexity :

  • Time Complexity : O(n2)
  • Space Complexity : O(1)

Method 1 : Code in C++

#include<bits/stdc++.h>
using namespace std;

int disjoint(int arr1[], int arr2[], int n, int m){
    
    for(int i=0; i<n; i++){
        for(int j=0; j<m; j++){
            if(arr1[i]==arr2[j]){
                return 0;   
            }
        }
    }
    return 1;
}

int main(){
    
    int arr1[] = {10, 20, 30, 67};
    int arr2[] = {20, 90, 80, 77, 23};
    int n = sizeof(arr1)/sizeof(arr1[0]);
    int m = sizeof(arr2)/sizeof(arr2[0]);
    
    if(disjoint(arr1, arr2, n, m))
    cout<<"Yes";
    
    else cout<<"No";
    
}

Output :

No

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Method 2 :

In this method first sort both the given integer arrays, then using the merge process we compare the elements in both arrays.

Method 2 : Code in C++

#include<bits/stdc++.h>
using namespace std;

int disjoint(int arr1[], int arr2[], int n, int m){
    
    sort(arr1, arr1+n);
    sort(arr2, arr2+m);
    
    // Check for same elements using merge like process
    int i = 0, j = 0;
    while (i < m && j < n)
    {
        if (arr1[i] < arr2[j])
            i++;
        else if (arr2[j] < arr1[i])
            j++;
        else /* if set1[i] == set2[j] */
            return 0;
    }
 
    return 1;
}

int main(){
    
    int arr1[] = {10, 20, 30, 67};
    int arr2[] = {20, 90, 80, 77, 23};
    int n = sizeof(arr1)/sizeof(arr1[0]);
    int m = sizeof(arr2)/sizeof(arr2[0]);
    
    if(disjoint(arr1, arr2, n, m))
    cout<<"Yes";
    
    else cout<<"No";
    
}

Output :

No

Method 3 :

In this method we use the concept of set.

  • Iterate through the first array and store every element in the set.
  • Iterate through the second array and check if any element is present in the set.
  • If present, then returns false, else ignore the element. 
  • If all elements of the second array are not present in the set, return true.
While loop in C

Method 3 : Code in C++

#include<bits/stdc++.h>
using namespace std;

int disjoint(int arr1[], int arr2[], int n, int m){
    
    set st;
 
    // Traverse the first set and store its elements in hash
    for (int i = 0; i < n; i++)
        st.insert(arr1[i]);
 
    // Traverse the second set and check if any element of it
    // is already in hash or not.
    for (int i = 0; i < m; i++)
        if (st.find(arr2[i]) != st.end())
            return 0;
 
    return 1;
}

int main(){
    
    int arr1[] = {10, 20, 30, 67};
    int arr2[] = {20, 90, 80, 77, 23};
    int n = sizeof(arr1)/sizeof(arr1[0]);
    int m = sizeof(arr2)/sizeof(arr2[0]);
    
    if(disjoint(arr1, arr2, n, m))
    cout<<"Yes";
    
    else cout<<"No";
    
}

Output :

No

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While loop in C