D. Take5

Codeforces

IDCF10100D

Time2000ms

Memory6MB

Difficulty—

English · Original

Formal · Original

Pay attention to the *memory limit* for this problem! You are given an array A of size N and a positive integer S. You need to find the number of ways W in which you can chose 5 elements with distinct positions such that their sum is equal to S. The first line contains two positive integer N, S (1 ≤ N ≤ 103, 0 ≤ S ≤ 2 * 109) - the size of the array and the queried sum. The next line contains N numbers Ai (0 ≤ Ai ≤ 4 * 108, 1 ≤ i ≤ N). Print the only integer W (0 ≤ W < 231) - the number of ways to chose the elements. ## Input The first line contains two positive integer N, S (1 ≤ N ≤ 103, 0 ≤ S ≤ 2 * 109) - the size of the array and the queried sum. The next line contains N numbers Ai (0 ≤ Ai ≤ 4 * 108, 1 ≤ i ≤ N). ## Output Print the only integer W (0 ≤ W < 231) - the number of ways to chose the elements. [samples]

**Definitions** Let $ N \in \mathbb{Z}^+ $, $ S \in \mathbb{Z}_{\geq 0} $. Let $ A = (a_1, a_2, \dots, a_N) $ be a sequence of integers with $ a_i \in \mathbb{Z}_{\geq 0} $. **Constraints** 1. $ 1 \leq N \leq 10^3 $ 2. $ 0 \leq S \leq 2 \cdot 10^9 $ 3. $ 0 \leq a_i \leq 4 \cdot 10^8 $ for all $ i \in \{1, \dots, N\} $ **Objective** Compute the number of 5-element subsets $ \{i_1, i_2, i_3, i_4, i_5\} \subseteq \{1, \dots, N\} $ with $ i_1 < i_2 < i_3 < i_4 < i_5 $ such that: $$ a_{i_1} + a_{i_2} + a_{i_3} + a_{i_4} + a_{i_5} = S $$

API Response (JSON)

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      "content": "Pay attention to the *memory limit* for this problem! You are given an array A of size N and a positive integer S. You need to find the number of ways W in which you can chose 5 elements with distinc",
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