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Divide N into K parts in the form (X, 2X, … , KX) for some value of X
  • Difficulty Level : Expert
  • Last Updated : 07 Jul, 2020
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Given a positive integer N and K, the task is to divide N into K parts such that the first part has a value X, the second part is 2X, and so on for some value of X. If such division is not possible then print -1.

Examples:

Input: N = 10, K = 4
Output: 1 2 3 4
Explanation:
If we take 1 as first number second number will be 2 third number will be 3 times first which is 3 and the last number will be 4 times third number so last number is 4. We can note that sum=1+2+3+4=10 which is the required sum.

Input N = 10, K = 3
Output: -1
Explanation:
Distributing N in 3 parts with given constraint is not possible.

Approach: To solve the problem mentioned above let’s to understand it’s mathematical implementation. Let the division be X1, X2, X3 up to XK where the second integer is X1 * 2, third one is X1 * 3 and the Kth one is X1 * K.



We know that,
=>  X_{1} + X_{2} + X_{3} + ... +  X_{K} = N
=> X_{1} + 2*X_{1} + 3*X_{1} + ... +  K*X_{1} = N
=> X_{1}( 1 + 2 + 3 + ... + K) = N
=> X_{1} * \frac{K*(K+1))}{2} = N, where ( 1 + 2 + 3 + … + K) = \frac{K*(K+1))}{2}
=> X_{1} =  \frac{2*N}{K*(K+1)}

So to solve the problem we have to follow the steps given below:

  • Calculate the value of K * (K + 1) and divide 2 * N by K * (K + 1) in order to get value of X1.
  • If X1 is not an integer in the above step then print -1 as there is no such division is possible.
  • To get the value of X2 we will multiply X1 by 2. Similarly, to get XK multiply X1 with K.
  • After finding all teh values print them.

Below is the implementation of above approach:

C++




// C++ program for the above approach
#include <iostream>
using namespace std;
typedef long long int ll;
  
// Function to find the division
void solve(int n, int k)
{
    int x1, d;
  
    // Calculating value of x1
    d = k * (k + 1);
  
    // Print -1 if division
    // is not possible
    if ((2 * n) % d != 0) {
        cout << "-1";
        return;
    }
  
    x1 = 2 * n / d;
  
    // Get the first number ie x1
    // then successively multiply
    // it by x1 k times by index number
    // to get the required answer
    for (int i = 1; i <= k; i++) {
        cout << x1 * i << " ";
    }
    cout << endl;
}
  
// Driver Code
int main()
{
    // Given N and K
    int n = 10, k = 4;
  
    // Function Call
    solve(n, k);
}

Java




// Java program for the above approach
import java.util.*;
class GFG{
  
// Function to find the division
static void solve(int n, int k)
{
    int x1, d;
  
    // Calculating value of x1
    d = k * (k + 1);
  
    // Print -1 if division
    // is not possible
    if ((2 * n) % d != 0
    {
        System.out.print("-1");
        return;
    }
  
    x1 = 2 * n / d;
  
    // Get the first number ie x1
    // then successively multiply
    // it by x1 k times by index number
    // to get the required answer
    for (int i = 1; i <= k; i++) 
    {
        System.out.print(x1 * i+ " ");
    }
    System.out.println();
}
  
// Driver Code
public static void main(String[] args)
{
    // Given N and K
    int n = 10, k = 4;
  
    // Function Call
    solve(n, k);
}
}
  
// This code is contributed by 29AjayKumar

Python3




# Python3 program for the above approach
  
# Function to find the division
def solve(n, k):
  
    # Calculating value of x1
    d = k * (k + 1);
  
    # Print -1 if division
    # is not possible
    if ((2 * n) % d != 0):
        print("-1");
        return;
      
  
    x1 = 2 * n // d;
  
    # Get the first number ie x1
    # then successively multiply
    # it by x1 k times by index number
    # to get the required answer
    for i in range(1, k + 1):
        print(x1 * i, end = " ");
  
# Driver Code
  
# Given N and K
n = 10; k = 4;
  
# Function Call
solve(n, k);
  
# This code is contributed by Code_Mech

C#




// Java program for the above approach
import java.util.*;
class GFG{
  
// Function to find the division
static void solve(int n, int k)
{
    int x1, d;
  
    // Calculating value of x1
    d = k * (k + 1);
  
    // Print -1 if division
    // is not possible
    if ((2 * n) % d != 0) 
    {
        System.out.print("-1");
        return;
    }
  
    x1 = 2 * n / d;
  
    // Get the first number ie x1
    // then successively multiply
    // it by x1 k times by index number
    // to get the required answer
    for (int i = 1; i <= k; i++) 
    {
        System.out.print(x1 * i+ " ");
    }
    System.out.println();
}
  
// Driver Code
public static void main(String[] args)
{
    // Given N and K
    int n = 10, k = 4;
  
    // Function Call
    solve(n, k);
}
}
  
// This code is contributed by 29AjayKumar
Output:
1 2 3 4

Time Complexity: O(K)
Auxiliary Space: O(1)

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