int getMissingNumber(int arr [],int low,int high,int diff)
{
if(high <= low)
{
printf("Must have two numbers!!!\n");
return 0;
}
int mid = (low+high)/2;
// element just after the mid is missing
if(arr[mid+1]-arr[mid] != diff)
return arr[mid]+diff;
// element just before the mid is missing
if(mid>0 && arr[mid]-arr[mid-1]!= diff)
return arr[mid-1]+diff;
// check if AP is till mid of array
if(arr[mid]==arr[0]+mid*diff)
{
return getMissingNumber(arr,mid+1,high,diff);
}
return getMissingNumber(arr,low,mid-1,diff);
}
/* Driver program to check above functions */
int main()
{
int arr[] = {2, 4, 8, 10, 12, 14};
int n = sizeof(arr)/sizeof(arr[0]);
printf("The missing element is %d", getMissingNumber(arr,0, n,2));
return 0;
}
int main(){
int array[] = { 1, 2, 3, 5, 6, 7, 8 };
int len = sizeof(array) / sizeof(array[0]);
printf("The missing number is %d", getMissingNumber(array, len));
printf("\nThe missing number is %d using XOR", getMissingNumberXOR(array, len));
}