Phone

1. fancy number

follow up: given n digits, find all n digits fancy numbers

Onsite

1. binary search
2. zig zag sort
3. max profit leetcode
4. quicksort
5. binary tree lock a node (a node can be locked only if all its ancestor and children are unlocked), log n implementation
6. find local max/min, log n implementation
7. given array, and operators +/-, get target n, need to use all element in array
8. n th fibonacci in log n time