problem325

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325. Maximum Size Subarray Sum Equals k (Medium)

Given an array nums and a target value k, find the maximum length of a subarray that sums to k. If there isn't one, return 0 instead.

Note:
The sum of the entire nums array is guaranteed to fit within the 32-bit signed integer range.

Example 1:

Input: nums = [1, -1, 5, -2, 3], k = 3
Output: 4 
Explanation: The subarray [1, -1, 5, -2] sums to 3 and is the longest.

Example 2:

Input: nums = [-2, -1, 2, 1], k = 1
Output: 2 
Explanation: The subarray [-1, 2] sums to 1 and is the longest.

Follow Up:
Can you do it in O(n) time?

Related Topics

[Hash Table]

Similar Questions

1. Minimum Size Subarray Sum (Medium)
2. Range Sum Query - Immutable (Easy)
3. Contiguous Array (Medium)
4. Subarray Product Less Than K (Medium)

Hints

Hint 1

Try to compute a sum of a subsequence very fast, i.e in O(1) … Think of prefix sum array.

Hint 2

Given S[i] a partial sum that starts at position 0 and ends at i, what can S[i - k] tell you ?

Hint 3

Use HashMap + prefix sum array.