What is Rerooting Technique?

The rerooting technique is an algorithmic method used in tree data structures to efficiently compute properties of nodes relative to different roots. This technique allows for the recalculation of node properties when the root of the tree changes. It is used in solving problems involving dynamic programming on trees, path queries, and subtree properties.

Rerooting techniques are typically used in the context of rooted trees in computational problems, such as dynamic programming on trees, network design, and more. The idea is to compute some values for a tree rooted at one node and then efficiently recompute the values for the tree rooted at other nodes.

To demonstrate rerooting techniques in Python, let’s consider a common problem: calculating the sum of distances from each node to all other nodes in an unweighted tree. This problem can be solved using rerooting techniques efficiently.