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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12. 		// your code goes here
  13. 		int arr[] = {1,5,-3,4,-9,9,2};
  14. 		int n = arr.length;
  15. 		System.out.println("maximum sum of two non overlapping subarrays  " + maxTwoOverLappingSubarrays(arr,n));
  16. 	}
  17. 	public static int maxTwoOverLappingSubarrays(int [] arr, int n){
  18. 		int[] prefixMaxSum = calculateMaxPrefixSum(arr,n);
  19. 		int[] suffixMaxSum = calculateMaxSuffixSum(arr,n);
  20.  
  21. 		int[] maxPrefixSum = new int[n];
  22. 		maxPrefixSum[0] = prefixMaxSum[0];
  23. 		for(int i=1;i<n;i++){
  24. 			maxPrefixSum[i] = Math.max(prefixMaxSum[i],maxPrefixSum[i-1]);
  25. 		}
  26.  
  27. 		int[] maxSuffixSum = new int[n];
  28. 		maxSuffixSum[n-1] = arr[n-1];
  29. 		for(int i=n-2;i>=0;i--){
  30. 			maxSuffixSum[i] = Math.max(suffixMaxSum[i],maxSuffixSum[i+1]);
  31. 		}
  32. 		int max = 0;
  33. 		for(int i=0;i<n-1;i++){
  34. 			max = Math.max(max,maxPrefixSum[i]+maxSuffixSum[i+1]);
  35.  
  36. 		}
  37. 		return max;
  38.  
  39. 	}
  40. 	public static int[] calculateMaxPrefixSum(int []arr, int n){
  41. 		int[] prefixMaxSum = new int[n];
  42. 		prefixMaxSum[0] = arr[0];
  43. 		int currentMax = arr[0];
  44. 		for(int i=1;i<n;i++){
  45. 			prefixMaxSum[i] = Math.max(0,Math.max(arr[i],arr[i]+currentMax));
  46. 			currentMax = prefixMaxSum[i];
  47. 		}
  48. 		return prefixMaxSum;
  49. 	}
  50. 	public static int[] calculateMaxSuffixSum(int[] arr, int n){
  51. 		int[] suffixMaxSum = new int[n];
  52. 		suffixMaxSum[n-1] = arr[n-1];
  53. 		int currentMax = arr[n-1];
  54. 		for(int i=n-2;i>=0;i--){
  55. 			suffixMaxSum[i] = Math.max(0,Math.max(arr[i],arr[i]+currentMax));
  56. 			currentMax = suffixMaxSum[i];
  57. 		}
  58. 		return suffixMaxSum;
  59. 	}
  60.  
  61. }
Success #stdin #stdout 0.15s 53544KB
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maximum sum of two non overlapping subarrays  18
https://ideone.com/HM7gU7
language:
Java (HotSpot 12)
created:
2 days ago
visibility:
public

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