Rajan Array

. A Rajan array has the following property.

   a[0] = a[1] + a[2] = a[3] + a[4] + a[5] = a[6] + a[7] + a[8] + a[9] = ...

The length of a Rajan array must be n*(n+1)/2 for some n.

Write a method named isRajanArray that returns 1 if its array argument is a Rajan array, otherwise it returns 0. If you are programming in Java or C# the function signature is

   int isRajanArray(int[ ] a)

If you are programming in C or C++, the function signature is

   int isRajanArray(int a[ ], int len) where len is the number of elements in a.

Examples

if a is	return	Reason
{2, 1, 1}	1	2 + 1 + 1
{2, 1, 1, 4, -1, -1}	1	2 = 1 + 1, 2 = 4 + -1 + -1
{6, 2, 4, 2, 2, 2, 1, 5, 0, 0}	1	6 = 2 + 4, 6 = 2 + 2 + 2, 6 = 1 + 5 + 0 + 0
{18, 9, 10, 6, 6, 6}	0	18 != 9 + 10
{-6, -3, -3, 8, -5, -4}	0	-6 != 8 + -5 + -4
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, -2, -1}	1	0 = 0 + 0, 0 = 0 + 0 + 0, 0 = 0 + 0 + 0 + 0, 0 = 1 + 1 + 1 + -2 + -1
{3, 1, 2, 3, 0}	0	The length of the array is 5, but 5 does not equal n*(n+1)/2 for any value of n.

Solution:

int isRajanArray(int[] arr){
 
 int sumLength = 0;
 
 for(int i=1; sumLength < arr.length; i++){
  sumLength += i;
 }
 
 if(sumLength != arr.length){
  return false;
 }
 
 //logic to check the sum
 int sum = arr[0];
 
 sumLength = 0;
 int index = 0;
 
 int sum2 = 0;
 for(int j =1; sumLength < arr.length; j++){
  sum2 = 0;
  
  for(int k=0; k<j; k++){
   sum2+=arr[index++];
  }
  if(sum != sum2){
     return false;
     }
 }
 
 return true;
 
 
}

Enjoy