Find the indices of the first two numbers that add to a target sum.
Print list frontward and backward.
Lucas and fibonacci series.
Get all pairs in the list that add to a sum.
Given some amount of money in a certain currency, please give me the change.
Mergesort a list.
Show that two trees are reflective.
T1:
0
/ \
/ \
1 2
/ \ / \
3 4 5 6
T2: T1 Reflective
0
/ \
/ \
2 1
/ \ / \
6 5 4 3
Reflective: If you place T2 on the left or right side of T1, it should close like a book.
Count the number of words with a given prefix.
Count the number of islands in a binary image.
DFS, BFS, DFS recursive, BFS recursive, shortest path.