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  1. Practice
  2. Algorithms
  3. Implementation
  4. Between Two Sets
  5. Discussions

Between Two Sets

  • yash3shah + 2 comments

    EDIT - 1:

    I've updated my code for better readability: I guees this will explain it a lot better.

    import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    
    private boolean canADivideI(int i, int[] a, int n){
        boolean answer = false;
        for(int j=0;j<n;j++){
                if(i%a[j] == 0){
                    if(j==n-1){
                        answer = true;
                    }
                }
                else{j=n;}
        }
        return answer;
    }
    
    private boolean canIDivideB(int i, int[] b, int m){
        boolean answer = false;
        for(int k=0;k<m;k++){
            if(b[k]%i ==0){
                if(k==m-1){
                    answer = true;
                }
            }
            else {k=m;}
        }   
        return answer;
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        Solution s = new Solution();
        int n = in.nextInt();
        int m = in.nextInt();
        int[] a = new int[n];
        int max = 100, min = 0, elementsFound = 0;
        for(int a_i=0; a_i < n; a_i++){
            a[a_i] = in.nextInt();
            //Look for Max in A and set that as the MIN 
            if(min < a[a_i]) {min = a[a_i];}
        }
        int[] b = new int[m];
        for(int b_i=0; b_i < m; b_i++){
            b[b_i] = in.nextInt();
            //Look for Min in B and set that as the MAX
            if(max > b[b_i]) {max = b[b_i];}
        }
        for(int i = min; i <=max; i++){
            if(s.canADivideI(i, a, n) && s.canIDivideB(i, b, m)){
                elementsFound++;   
            }
        }
        System.out.println(elementsFound);
    }
}

    I did something simmilar, I guess it is an optimized version.

    import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int m = in.nextInt();
        int[] a = new int[n];
        int max = 100, min = 0, answr = 0;
        for(int a_i=0; a_i < n; a_i++){
            a[a_i] = in.nextInt();
            //Look for Max in A and set that as the MIN 
            if(min < a[a_i]) {min = a[a_i];}
        }
        int[] b = new int[m];
        for(int b_i=0; b_i < m; b_i++){
            b[b_i] = in.nextInt();
            //Look for Min in B and set that as the MAX
            if(max > b[b_i]) {max = b[b_i];}
        }
        for(int i = min; i <= max; i++){
            for(int j = 0; j < n; j++){
                if(i%a[j] == 0){
                    if(j == n-1){
                        for(int k = 0; k < m; k++){
                            if(b[k]%i == 0){
                                if(k == m-1){
                                    answr++;
                                }
                            }
                            else {k = m;}
                        }
                    }
                }
                else{j = n;}
            }
        }
        System.out.println(answr);
    }
}
    • joyshurock + 1 comment

      Can you explain a bit the algorithm behind the second part of your code works? ( for(int i = min; i <= max; i++){}) Thank you!

      • yash3shah + 0 comments

        I know it's been a long time since you asked this question, and I apologize for not being active here for a while. But if you are still interested, Here is my answer:

        Min and Max are the Maximum value in A and Minimum value in B respectively - Why I chose min from A and max from B you ask? If you think about the question, we need to find element X that can be divided by any A[i] and can divide any B[i]. So logically the number lies between Max(A) and Min(B), the minimum number would be min - Maximum in A and the the maximum number would be max - Minimum in B.

        The For loop only needs to be run through those numbers - even though the limit is 0 <= a[i],b[i] <= 100. As the numbers we care about are only the ones present in the set {min,...,max} inclusive.

    • Arpit7694 + 1 comment

      can somebody please Explain this part to me?

      if(j == n-1){ for(int k = 0; k < m; k++){ if(b[k]%i == 0){ if(k == m-1){ answr++; } }

      • yash3shah + 0 comments

        I know it's been a long time since you asked this question, and I apologize for not being active here for a while. But if you are still interested, Here is my answer:

        The for loop before this statement finds that the Element I is divisible by all the elements in array A, a[j]. Thus at any given point if any element a[j] cannot divide I, it should shut off and move on to the next element I + 1.

        How do we know if all the elements in array A actually were able to divide I? - If you are still in the loop, and your j is n-1, meaning, you've reached the last element in array A (As the n is the length of A), all the elements at position (J==n-1) satisfied the division (otherwise, the loop would've exited - See j = n in else condition - that is exit logic).

        Now if all a[j] were satisfying, we need to check if the element I can divide all elements in B, b[k]. The same logic used in checking if all elements in B are divisible by I - meaning if (K==m-1) where m is length of B - All elements at position m-1 were divisible by I.

        At this point we found our element - So answer = answer + 1.