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Count pairs from two arrays whose modulo operation yields K in C++
We are given two arrays containing positive numbers and a value K. The goal is to find unique pairs of elements of arrays such that pairs of type (A,B) has A%B=K or B%A=K and A belongs to the first array and B belongs to the second array.
Let us understand with examples
Input − arr_1[] = {1,2,5,3,4}; arr_2[] = {7,1,3}; k=2
Output − Count of pairs from two arrays whose modulo operation yields K are − 2
Explanation − The pairs are (5,7) - (arr_1[2],arr_2[1]) 7%5=2 and (5,3) - (arr_1[2],arr_2[2]) 5%3=2
Input − arr_1[] = {2,5}; arr_2[] = {3,7}; k=1
Output − Count of pairs from two arrays whose modulo operation yields K are − 2
Explanation − The pairs are (2,3) - (arr_1[0],arr_2[0]) 3%2=1 and (2,7) - (arr_1[0],arr_2[1]) 7%2=1
Approach used in the below program is as follows
In this approach we will traverse both arrays using for loop. Insert pairs to set<pair<int, int> > se in which A%B=k or B%A=k, where A belongs to arr_1 and B belongs to arr_2. At the end size of set se is the number of unique pairs from two arrays whose modulo operation yields k.
Take integer arrays arr_1[] and arr_2[] with positive elements and lengths as size_arr_1 and size_arr_2.
Take integers k.
Function modulo_pairs(int arr_1[], int arr_2[], int size_arr_1, int size_arr_2, int k) takes both arrays and their lengths and returns the pairs such that the modulo operation of elements of both arrays yields k.
Take the initial value of count as 0.
Take set<pair<int, int> > se; of pairs <int,int>.
Start traversing arr_1[] from i=0 to i<size_arr_1 and arr_2[] from j=0 to j<size_arr_2.
For each pair arr_1[i], arr_2[j], check if arr_1[i]>arr_2[j]. If yes check if arr_1[i]%arr_2[j]==k. If true then make a pair of arr_1[i] and arr_2[j] and insert to set se.
Else check if arr_2[j]%arr_1[i]==k. If true then make a pair of arr_1[i] and arr_2[j] and insert to set se.
Calculate count as se.size(). For count of unique pairs.
Return count as result.
Example
#include <bits/stdc++.h>
using namespace std;
int modulo_pairs(int arr_1[], int arr_2[], int size_arr_1, int size_arr_2, int k){
int count = 0;
set<pair<int, int> > se;
for (int i = 0; i < size_arr_2; i++){
for (int j = 0; j < size_arr_1; j++){
if (arr_1[i] > arr_2[j]){
if (arr_1[i] % arr_2[j] == k){
se.insert(make_pair(arr_1[i], arr_2[j]));
}
}
else{
if (arr_2[j] % arr_1[i] == k){
se.insert(make_pair(arr_2[j], arr_1[i]));
}
}
}
}
count = se.size();
return count;
}
int main(){
int arr_1[] = { 2, 7, 1, 9 };
int arr_2[] = { 4, 10, 3, 10 };
int size_arr_1 = sizeof(arr_1) / sizeof(arr_1[0]);
int size_arr_2 = sizeof(arr_2) / sizeof(arr_2[0]);
int k = 3;
cout<<"Count of pairs from two arrays whose modulo operation yields K are:"<<modulo_pairs(arr_1, arr_2, size_arr_1, size_arr_2, k);
return 0;
}Output
If we run the above code it will generate the following output −
Count of pairs from two arrays whose modulo operation yields K are: 2
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