Blocks with a given total

Problem

A bank lists the net change of n days. Count the blocks of consecutive days whose changes add up to exactly k. The numbers can be negative or zero.

Example

Input

4 7
3 4 7 2

Output

The blocks [3, 4] and [7].

Try the problem first. Open one hint at a time.

Hint 1

A block from i to j has sum k when prefix[j + 1] - prefix[i] = k.

Hint 2

Count earlier prefixes equal to prefix - k. Start the Counter with {0: 1}.

Write your Python code, run it on the examples and submit it to hidden tests.