CF2001E1 Deterministic Heap (Easy Version)

This is the easy version of the problem. The difference between the two versions is the definition of deterministic max-heap, time limit, and constraints on $ n $ and $ t $ . You can make hacks only if both versions of the problem are solved. Consider a perfect binary tree with size $ 2^n - 1 $ , with nodes numbered from $ 1 $ to $ 2^n-1 $ and rooted at $ 1 $ . For each vertex $ v $ ( $ 1 \le v \le 2^{n - 1} - 1 $ ), vertex $ 2v $ is its left child and vertex $ 2v + 1 $ is its right child. Each node $ v $ also has a value $ a_v $ assigned to it. Define the operation $ \mathrm{pop} $ as follows: 1. initialize variable $ v $ as $ 1 $ ; 2. repeat the following process until vertex $ v $ is a leaf (i.e. until $ 2^{n - 1} \le v \le 2^n - 1 $ ); 1. among the children of $ v $ , choose the one with the larger value on it and denote such vertex as $ x $ ; if the values on them are equal (i.e. $ a_{2v} = a_{2v + 1} $ ), you can choose any of them; 2. assign $ a_x $ to $ a_v $ (i.e. $ a_v := a_x $ ); 3. assign $ x $ to $ v $ (i.e. $ v := x $ ); 3. assign $ -1 $ to $ a_v $ (i.e. $ a_v := -1 $ ). Then we say the $ \mathrm{pop} $ operation is deterministic if there is a unique way to do such operation. In other words, $ a_{2v} \neq a_{2v + 1} $ would hold whenever choosing between them. A binary tree is called a max-heap if for every vertex $ v $ ( $ 1 \le v \le 2^{n - 1} - 1 $ ), both $ a_v \ge a_{2v} $ and $ a_v \ge a_{2v + 1} $ hold. A max-heap is deterministic if the $ \mathrm{pop} $ operation is deterministic to the heap when we do it for the first time. Initially, $ a_v := 0 $ for every vertex $ v $ ( $ 1 \le v \le 2^n - 1 $ ), and your goal is to count the number of different deterministic max-heaps produced by applying the following operation $ \mathrm{add} $ exactly $ k $ times: - Choose an integer $ v $ ( $ 1 \le v \le 2^n - 1 $ ) and, for every vertex $ x $ on the path between $ 1 $ and $ v $ , add $ 1 $ to $ a_x $ . Two heaps are considered different if there is a node which has different values in the heaps. Since the answer might be large, print it modulo $ p $ .

N/A

N/A

For the first testcase, there is only one way to generate $ a $ , and such sequence is a deterministic max-heap, so the answer is $ 1 $ . For the second testcase, if we choose $ v = 1 $ and do the operation, we would have $ a = [1, 0, 0] $ , and since $ a_2 = a_3 $ , we can choose either of them when doing the first $ \mathrm{pop} $ operation, so such heap is not a deterministic max-heap. And if we choose $ v = 2 $ , we would have $ a = [1, 1, 0] $ , during the first $ \mathrm{pop} $ , the following would happen: - initialize $ v $ as $ 1 $ - since $ a_{2v} > a_{2v + 1} $ , choose $ 2v $ as $ x $ , then $ x = 2 $ - assign $ a_x $ to $ a_v $ , then $ a = [1, 1, 0] $ - assign $ x $ to $ v $ , then $ v = 2 $ - since $ v $ is a leaf, assign $ -1 $ to $ a_v $ , then $ a = [1, -1, 0] $ Since the first $ \mathrm{pop} $ operation is deterministic, this is a deterministic max-heap. Also, if we choose $ v = 3 $ , $ a $ would be a deterministic max-heap, so the answer is $ 2 $ .