Tree Maximum Matching Greedy

Problem

Compute the maximum matching size of a tree with n nodes.

Process nodes in reverse BFS order (leaves first): whenever a node and its parent are both unmatched, match them. This greedy is optimal on trees. edges is a list of [u, v] pairs and the tree is rooted at 0.

Hint

Matching a leaf with its parent never hurts: the parent has no better use.

Test cases

case 1

in: [4,[[0,1],[1,2],[2,3]]]

expected: 2

case 2

in: [4,[[0,1],[0,2],[0,3]]]

expected: 1

case 3

in: [3,[[0,1],[1,2]]]

expected: 1

case 4

in: [2,[[0,1]]]

expected: 1

case 5

in: [1,[]]

expected: 0

Starter codePython

def tree_max_matching(n, edges):
    # Your code here
    pass

5 test cases · run your code against them in the editor