Trees, Segment Trees, DFS
Given a tree with N nodes and N-1 edges and provided with values in each and every node ( being only zero or one), you have to deal with Queries as followed:
swap the value of the node mentioned. ( 1 -> 0 and vice-versa).
Find the total number of set nodes below the Mth, where the Mth node lies in the path between the root node 1 and Uth node .
Pre process the tree by generating the three arrays.
Count of total nodes below the Mth node.
Index of elements in the DFS traversal array
- After fetching all the data, build the segment tree, placing all the values of the nodes in the tree.
- For every Query, we input the Mth node to find the total set nodes below it (Excluding it).
- The left and right ranges will be defined as
L - index_in_DFS_traversal_array[M]+1
R - index_in_DFS_traversal_array[M]+subtree_size[M]-1)
- For Swapping the value of the Mth node, we will pass the
index_in_DFS_traversal_array[M] in our Update position parameter.
The rest remains the same as it happens in a segment tree.
Let us know your methods in the comment sections.
Setter’s solution : Can be found here