Dsa
Prefix Sum
Medium
Matching-End Sum
Find the length of the longest subarray whose elements sum to exactly S, with the additional constraint that the first and last elements of the subarray must be equal.
Input Format:
The first line contains N and S.
The second line contains N integers.
Output Format:
A single integer representing the length of the longest such subarray. If none exist, output 0.
Example:
Input:
5 4
2 1 2 2 2
Output:
2
Explanation: The subarray [2, 2] at the end has sum 4 and starts/ends with 2. Length is 2.
Key concepts
prefix_sumhash_mapsubarray
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