DSA Crash Course [Part 39] - Depth First Values Approach

In this lesson, Alvin explores the strategy to solving the following interview problem:

Write a function, depth_first_values, that takes in the root of a binary tree. The function should return a list containing all values of the tree in depth-first order.

a = Node('a')
b = Node('b')
c = Node('c')
d = Node('d')
e = Node('e')
f = Node('f')
a.left = b
a.right = c
b.left = d
b.right = e
c.right = f
#      a
#    /   \
#   b     c
#  / \     \
# d   e     f

depth_first_values(a)
#   -> ['a', 'b', 'd', 'e', 'c', 'f']

a = Node('a')
b = Node('b')
c = Node('c')
d = Node('d')
e = Node('e')
f = Node('f')
g = Node('g')
a.left = b
a.right = c
b.left = d
b.right = e
c.right = f
e.left = g
#      a
#    /   \
#   b     c
#  / \     \
# d   e     f
#    /
#   g

depth_first_values(a)
#   -> ['a', 'b', 'd', 'e', 'g', 'c', 'f']

a = Node('a')
#     a

depth_first_values(a)
#   -> ['a']

If you need additional support taking these DSA skills and actually applying them, take Alvin's complete data structures and algorithms course on Structy. You can try out the concepts yourself in their interactive code editor and learn advanced DSA patterns like stack exhaustive recursion.

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