Count of operations to make all elements of array a[] equal to its min element by performing a[i] – b[i]

Last Updated : 12 Jul, 2025

Given two array a[] and b[] of size N, the task is to print the count of operations required to make all the elements of array a[i] equal to its minimum element by performing a[i] - b[i] where its always a[i] >= b[i]. If it is not possible then return -1.
Example:

Input: a[] = {5, 7, 10, 5, 15} b[] = {2, 2, 1, 3, 5}
Output: 8
Explanation:
Input array is a[] = 5, 7, 10, 5, 15 and b[] = 2, 2, 1, 3, 5. The minimum from a[] is 5.
Now for a[0] we don't have to perform any operation since its already 5.
For i = 1, a[1] - b[1] = 7 - 2 = 5. (1 operation)
For i = 2, a[2] - b[2] = 10 - 1 = 9 - 1 = 8 - 1 = 7 - 1 = 6 - 1 = 5 (5 operation)
For i = 3, a[3] = 5
For i = 4, a[4] - b[4] = 15 - 5= 10 - 5 = 5 (2 operation)
The total number of operations required is 8.
Input: a[] = {1, 3, 2} b[] = {2, 3, 2}
Output:-1
Explanation:
It is not possible to convert the array a[] into equal elements.

Approach: To solve the problem mentioned above follow the steps given below:

Find minimum from array a[]. Initialize a variable ans = -1 that stores resultant subtractions operation.
Iterate from minimum element of array a[] to 0 and initialize variable curr to 0 that stores the count subtraction to make the array element equal.
Traverse in the array and check if a[i] is not equal to x which is the minimum element in the first array, then make it equal to minimum else update curr equal to zero.
Check if curr is not equal to 0 then update ans as curr finally return the ans.

Below is the implementation of above approach:

C++

// C++ program to count the operations
// to make all elements of array a[]
// equal to its min element
// by performing a[i] – b[i]

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

// Function to convert all Element of
// first array equal using second array
int findMinSub(int a[], int b[], int n)
{
    // Get the minimum from first array
    int min = INT_MAX;
    for (int i = 0; i < n; i++) {
        if (a[i] < min)
            min = a[i];
    }

    // Variable that stores count of
    // resultant required subtraction
    // to Convert all elements equal
    int ans = -1;

    for (int x = min; x >= 0; x--)

    {
        // Stores the count subtraction to
        // make the array element
        // equal for each iteration
        int curr = 0;

        // Traverse the array and check if
        // a[i] is not equal to x then
        // Make it equal to minimum else
        // update current equal to zero
        for (int i = 0; i < n; i++) {
            if (a[i] != x) {

                if (b[i] > 0
                    && (a[i] - x) % b[i] == 0) {
                    curr += (a[i] - x) / b[i];
                }
                else {
                    curr = 0;
                    break;
                }
            }
        }
        // Check if curr is not equal to
        // zero then update the answer
        if (curr != 0) {
            ans = curr;
            break;
        }
    }

    return ans;
}

// Driver code
int main()
{

    int a[] = { 5, 7, 10, 5, 15 };
    int b[] = { 2, 2, 1, 3, 5 };

    int n = sizeof(a) / sizeof(a[0]);

    cout << findMinSub(a, b, n);
    return 0;
}

Java

// Java program to count the operations 
// to make all elements of array a[] 
// equal to its min element 
// by performing a[i] – b[i] 
import java.util.*; 

class GFG{ 

// Function to convert all element of 
// first array equal using second array 
static int findMinSub(int a[], int b[], int n) 
{ 
    
    // Get the minimum from first array 
    int min = Integer.MAX_VALUE; 
    for(int i = 0; i < n; i++) 
    { 
    if (a[i] < min) 
        min = a[i]; 
    } 

    // Variable that stores count of 
    // resultant required subtraction 
    // to Convert all elements equal 
    int ans = -1; 

    for(int x = min; x >= 0; x--) 
    { 
        
    // Stores the count subtraction 
    // to make the array element 
    // equal for each iteration 
    int curr = 0; 
        
    // Traverse the array and check 
    // if a[i] is not equal to x then 
    // Make it equal to minimum else 
    // update current equal to zero 
    for(int i = 0; i < n; i++) 
    { 
        if (a[i] != x) 
        { 
            if (b[i] > 0 && 
                (a[i] - x) % b[i] == 0) 
            { 
                curr += (a[i] - x) / b[i]; 
            } 
            else
            { 
                curr = 0; 
                break; 
            } 
        } 
    } 
        
    // Check if curr is not equal to 
    // zero then update the answer 
    if (curr != 0) 
    { 
        ans = curr; 
        break; 
    } 
    } 
    return ans; 
} 

// Driver code 
public static void main(String[] args) 
{ 
    int a[] = { 5, 7, 10, 5, 15 }; 
    int b[] = { 2, 2, 1, 3, 5 }; 
    int n = a.length; 

    System.out.print(findMinSub(a, b, n)); 
} 
} 

// This code is contributed by 29AjayKumar

Python3

# Python3 program to count the operations
# to make all elements of array a[]
# equal to its min element
# by performing a[i] – b[i]

# Function to convert all element of
# first array equal using second array
def findMinSub(a, b, n):
    
    # Get the minimum from first array
    min = a[0]
    for i in range(0, n):
        if a[i] < min:
            min = a[i]
            
    # Variable that stores count of 
    # resultant required subtraction 
    # to Convert all elements equal 
    ans = -1
    for x in range(min, -1, -1):
        
        # Stores the count subtraction
        # to make the array element
        # equal for each iteration
        curr = 0

        # Traverse the array and check
        # if a[i] is not equal to x then
        # Make it equal to minimum else
        # update current equal to zero
        for i in range(0, n):
            if a[i] != x:
                
                if (b[i] > 0 and 
                   (a[i] - x) % b[i] == 0):
                    curr += (a[i] - x) // b[i]
                else:
                    curr = 0
                    break

        # Check if curr is not equal to
        # zero then update the answer
        if curr != 0:
            ans = curr
            break
        
    return ans

# Driver code
a = [ 5, 7, 10, 5, 15 ]
b = [ 2, 2, 1, 3, 5 ]
n = len(a)

print(findMinSub(a, b, n))

# This code is contributed by jrishabh99

// C# program to count the operations 
// to make all elements of array a[] 
// equal to its min element 
// by performing a[i] – b[i] 
using System; 
class GFG{ 

// Function to convert all element of 
// first array equal using second array 
static int findMinSub(int []a, int []b, int n) 
{ 
    
    // Get the minimum from first array 
    int min = Int32.MaxValue; 
    
    for(int i = 0; i < n; i++) 
    { 
        if (a[i] < min) 
            min = a[i]; 
    } 

    // Variable that stores count of 
    // resultant required subtraction 
    // to Convert all elements equal 
    int ans = -1; 

    for(int x = min; x >= 0; x--) 
    { 
        
        // Stores the count subtraction 
        // to make the array element 
        // equal for each iteration 
        int curr = 0; 
            
        // Traverse the array and check 
        // if a[i] is not equal to x then 
        // Make it equal to minimum else 
        // update current equal to zero 
        for(int i = 0; i < n; i++) 
        { 
            if (a[i] != x) 
            { 
                if (b[i] > 0 && 
                    (a[i] - x) % b[i] == 0) 
                { 
                    curr += (a[i] - x) / b[i]; 
                } 
                else
                { 
                    curr = 0; 
                    break; 
                } 
            } 
        } 
            
        // Check if curr is not equal to 
        // zero then update the answer 
        if (curr != 0) 
        { 
            ans = curr; 
            break; 
        } 
    } 
    return ans; 
} 

// Driver code 
public static void Main() 
{ 
    int []a = { 5, 7, 10, 5, 15 }; 
    int []b = { 2, 2, 1, 3, 5 }; 
    int n = a.Length; 

    Console.Write(findMinSub(a, b, n)); 
} 
} 

// This code is contributed by Code_Mech

JavaScript

<script>
// javascript program to count the operations 
// to make all elements of array a 
// equal to its min element 
// by performing a[i] – b[i] 

    // Function to convert all element of
    // first array equal using second array
    function findMinSub(a , b , n) {

        // Get the minimum from first array
        var min = Number.MAX_VALUE;
        for (i = 0; i < n; i++) {
            if (a[i] < min)
                min = a[i];
        }

        // Variable that stores count of
        // resultant required subtraction
        // to Convert all elements equal
        var ans = -1;

        for (x = min; x >= 0; x--) {

            // Stores the count subtraction
            // to make the array element
            // equal for each iteration
            var curr = 0;

            // Traverse the array and check
            // if a[i] is not equal to x then
            // Make it equal to minimum else
            // update current equal to zero
            for (i = 0; i < n; i++) {
                if (a[i] != x) {
                    if (b[i] > 0 && (a[i] - x) % b[i] == 0) {
                        curr += (a[i] - x) / b[i];
                    } else {
                        curr = 0;
                        break;
                    }
                }
            }

            // Check if curr is not equal to
            // zero then update the answer
            if (curr != 0) {
                ans = curr;
                break;
            }
        }
        return ans;
    }

    // Driver code
        var a = [ 5, 7, 10, 5, 15 ];
        var b = [ 2, 2, 1, 3, 5 ];
        var n = a.length;

        document.write(findMinSub(a, b, n));

// This code is contributed by aashish1995
</script>

Output:

Time Complexity: O(min*n) // min is the minimum element in the array
Auxiliary Space: O(1)

Samdare B

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Article Tags :

Count of operations to make all elements of array a[] equal to its min element by performing a[i] – b[i]

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