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Split array into subarrays such that sum of difference between their maximums and minimums is maximum
  • Last Updated : 05 May, 2021

Given an array arr[] consisting of N integers, the task is to split the array into subarrays such that the sum of the difference between the maximum and minimum elements for all the subarrays is maximum.

Examples :

Input: arr[] = {8, 1, 7, 9, 2}
Output: 14
Explanation:
Consider splitting the given array into subarrays as {8, 1} and {7, 9, 2}. Now, the difference between maximum and minimum elements are:

  • {8, 1}: Difference is (8 – 1) = 7.
  • {7, 9, 2}: Difference is (9 – 2) = 7.

Therefore, the sum of the difference is 7 + 7 = 14.

Input: arr[] = {1, 2, 1, 0, 5}
Output: 6



Approach: The given problem can be solved by using Dynamic Programming. Follow the steps to solve the problem:

  • Initialize an array, say dp[], where dp[i] represents the maximum sum of the difference between the maximum and minimum element for all the subarray for the first i array element.
  • Initialize dp[0] as 0.
  • Traverse the given array over the range [1, N – 1] and perform the following steps:
    • Initialize a variable, say min as arr[i], that stores the minimum element over the range [0, i].
    • Initialize a variable, say max as arr[i], that stores the maximum element over the range [0, i].
    • Iterate over the range [0, i] using the variable j in the reverse order and perform the following steps:
      • Update the value of min as the minimum of min and arr[j].
      • Update the value of max as the minimum of max and arr[j].
      • Update the value of  dp[j] to the maximum of dp[j] and (max – min + dp[i]).
  • After completing the above steps, print the value of dp[N – 1] as the result.

Below is the implementation of the above approach :

C++




// C++ program for the above approach
#include <bits/stdc++.h>
using namespace std;
 
// Function to find maximum sum of
// difference between maximums and
// minimums in the splitted subarrays
int getValue(int arr[], int N)
{
    int dp[N];
    memset(dp, 0, sizeof(dp));
 
    // Base Case
    dp[0] = 0;
 
    // Traverse the array
    for(int i = 1; i < N; i++)
    {
 
        // Stores the maximum and
        // minimum elements upto
        // the i-th index
        int minn = arr[i];
        int maxx = arr[i];
 
        // Traverse the range [0, i]
        for(int j = i; j >= 0; j--)
        {
 
            // Update the minimum
            minn = min(arr[j], minn);
 
            // Update the maximum
            maxx = max(arr[j], maxx);
 
            // Update dp[i]
            dp[i] = max(dp[i], maxx - minn +
                   ((j >= 1) ? dp[j - 1] : 0));
        }
    }
 
    // Return the maximum
    // sum of difference
    return dp[N - 1];
}
 
// Driver code
int main()
{
    int arr[] = { 8, 1, 7, 9, 2 };
    int N = sizeof(arr) / sizeof(arr[0]);
    cout << getValue(arr, N);
 
    return 0;
}
 
// This code is contributed by Kingash

Java




// Java program for the above approach
 
import java.util.*;
public class Main {
 
    // Function to find maximum sum of
    // difference between maximums and
    // minimums in the splitted subarrays
    static int getValue(int[] arr, int N)
    {
        int dp[] = new int[N];
 
        // Base Case
        dp[0] = 0;
 
        // Traverse the array
        for (int i = 1; i < N; i++) {
 
            // Stores the maximum and
            // minimum elements upto
            // the i-th index
            int min = arr[i];
            int max = arr[i];
 
            // Traverse the range [0, i]
            for (int j = i; j >= 0; j--) {
 
                // Update the minimum
                min = Math.min(arr[j], min);
 
                // Update the maximum
                max = Math.max(arr[j], max);
 
                // Update dp[i]
                dp[i] = Math.max(
                    dp[i],
                    max - min + ((j >= 1)
                                     ? dp[j - 1]
                                     : 0));
            }
        }
 
        // Return the maximum
        // sum of difference
        return dp[N - 1];
    }
 
    // Driver Code
    public static void main(String args[])
    {
        int arr[] = { 8, 1, 7, 9, 2 };
        int N = arr.length;
        System.out.println(getValue(arr, N));
    }
}

C#




// C# program for the above approach
using System;
 
class GFG{
 
// Function to find maximum sum of
// difference between maximums and
// minimums in the splitted subarrays
static int getValue(int[] arr, int N)
{
    int[] dp = new int[N];
 
    // Base Case
    dp[0] = 0;
 
    // Traverse the array
    for(int i = 1; i < N; i++)
    {
         
        // Stores the maximum and
        // minimum elements upto
        // the i-th index
        int min = arr[i];
        int max = arr[i];
 
        // Traverse the range [0, i]
        for(int j = i; j >= 0; j--)
        {
             
            // Update the minimum
            min = Math.Min(arr[j], min);
 
            // Update the maximum
            max = Math.Max(arr[j], max);
 
            // Update dp[i]
            dp[i] = Math.Max(
                dp[i],
                max - min + ((j >= 1) ?
                     dp[j - 1] : 0));
        }
    }
 
    // Return the maximum
    // sum of difference
    return dp[N - 1];
}
 
// Driver Code
static public void Main()
{
    int[] arr = { 8, 1, 7, 9, 2 };
    int N = arr.Length;
     
    Console.Write(getValue(arr, N));
}
}
 
// This code is contributed by code_hunt

Python3




# python 3 program for the above approach
 
# Function to find maximum sum of
# difference between maximums and
# minimums in the splitted subarrays
def getValue(arr, N):
    dp = [0 for i in range(N)]
     
    # Traverse the array
    for i in range(1, N):
       
        # Stores the maximum and
        # minimum elements upto
        # the i-th index
        minn = arr[i]
        maxx = arr[i]
         
        j = i
         
        # Traverse the range [0, i]
        while(j >= 0):
           
            # Update the minimum
            minn = min(arr[j], minn)
 
            # Update the maximum
            maxx = max(arr[j], maxx)
 
            # Update dp[i]
            dp[i] = max(dp[i], maxx - minn + (dp[j - 1] if (j >= 1) else 0))
            j -= 1
 
    # Return the maximum
    # sum of difference
    return dp[N - 1]
 
# Driver code
if __name__ == '__main__':
    arr = [8, 1, 7, 9, 2]
    N = len(arr)
    print(getValue(arr, N))
 
    # This code is contributed by SURENDRA_GANGWAR.

Javascript




<script>
 
// JavaScript program to implement
// the above approach
 
    // Function to find maximum sum of
    // difference between maximums and
    // minimums in the splitted subarrays
    function getValue(arr, N)
    {
        let dp = Array.from({length: N}, (_, i) => 0);
  
        // Base Case
        dp[0] = 0;
  
        // Traverse the array
        for (let i = 1; i < N; i++) {
  
            // Stores the maximum and
            // minimum elements upto
            // the i-th index
            let min = arr[i];
            let max = arr[i];
  
            // Traverse the range [0, i]
            for (let j = i; j >= 0; j--) {
  
                // Update the minimum
                min = Math.min(arr[j], min);
  
                // Update the maximum
                max = Math.max(arr[j], max);
  
                // Update dp[i]
                dp[i] = Math.max(
                    dp[i],
                    max - min + ((j >= 1)
                                     ? dp[j - 1]
                                     : 0));
            }
        }
  
        // Return the maximum
        // sum of difference
        return dp[N - 1];
    }
 
// Driver code
 
     
        let arr = [ 8, 1, 7, 9, 2 ];
        let N = arr.length;
        document.write(getValue(arr, N));
           
</script>
Output: 
14

 

Time Complexity: O(N2)
Auxiliary Space: O(N)

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