Hi
I have one solution probably this might work.
Since the numbers are all unique you can find the sum of all the
numbers
in the array.
Also find the sum of n numbers n*(n+1)/2.
Subtract the second one from the first one you will get the number.
Thanks and Regards,
Girish Dinne
for example
1 2 3 4 5 6 7 8 9 9
So there are 10 number with all the 9 unique numbers.
So find the sum of 9 numbers 9*(9+1)/2 = 45
Find the sum of the given array 54
Subtract 54 -45 you will get the answer.
but this work if all the number from 1 to n-1 are there in the array.
