Tip 1 : Practice questions on DS Algorithm ( array/string/DP/trees)
Tip 2 : Prepare SQL queries and normalization.
Tip 1 : Descriptive
Tip 2 : Work ex should be prioritized.
It was easy and standard questions were asked.



Do not allocate extra space for another array. You need to do this by modifying the given input array in place with O(1) extra memory.
'n' = 5, 'arr' = [1 2 2 2 3].
The new array will be [1 2 3].
So our answer is 3.
Create a temporary array temp[] to store unique elements.
Traverse input array and one by one copy unique elements of arr[] to temp[]. Also keep track of count of unique elements. Let this count be h.
Copy h elements from temp[] to arr[] and return j
Medium questions on tree



1
/ \
2 3
The root to leaf path 1->2 represents the number 12.
The root to leaf path 1->3 represents the number 13.
The total sum of all the possible root to leaf paths is 12+13 = 25
The output may be very large, return the answer after taking modulus with (10^9+7).
The idea is to do a preorder traversal of the tree. In the preorder traversal, keep track of the value calculated till the current node, let this value be val. For every node, we update the val as val*10 plus node’s data.
It was easy and standard questions were asked.

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What is recursion?