How hard is LeetCode 325. Maximum Size Subarray Sum Equals k?

LeetCode 325. Maximum Size Subarray Sum Equals k is rated Medium on LeetCode.

What is the time complexity of LeetCode 325. Maximum Size Subarray Sum Equals k?

The Python solution on this page runs in O(n).

What is the space complexity of LeetCode 325. Maximum Size Subarray Sum Equals k?

The Python solution on this page uses O(n), where n is the length of the array \textit{nums} auxiliary space.

What topics does LeetCode 325. Maximum Size Subarray Sum Equals k cover?

LeetCode 325. Maximum Size Subarray Sum Equals k is tagged Array, Hash Table and Prefix Sum on LeetCode.

Is LeetCode 325. Maximum Size Subarray Sum Equals k a premium problem?

Yes. LeetCode 325. Maximum Size Subarray Sum Equals k is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.

Maximum Size Subarray Sum Equals k — LeetCode 325 Python Solution

MediumLeetCode PremiumArrayHash TablePrefix Sum

Problem: #325
Pattern: Prefix Sum
Reading time: 2 min
Source: leetcode.com

The problem

Given an integer array nums and an integer k, return the maximum length of a subarray that sums to k. If there is not one, return 0 instead.

Example

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.

Python solution

Python

class Solution:
    def maxSubArrayLen(self, nums: List[int], k: int) -> int:
        d = {0: -1}
        ans = s = 0
        for i, x in enumerate(nums):
            s += x
            if s - k in d:
                ans = max(ans, i - d[s - k])
            if s not in d:
                d[s] = i
        return ans

Complexity

Measure	Complexity
Time	O(n)
Space	O(n), where n is the length of the array \textit{nums} auxiliary

Pattern: Prefix Sum

Precompute running totals once so any range query becomes a single subtraction. LeetCode 325. Maximum Size Subarray Sum Equals k is filed here because LeetCode tags it Prefix Sum, which is the vocabulary this hub collects.

The prefix sum guide has the Python template for the pattern and the 157 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 325. Maximum Size Subarray Sum Equals k?: LeetCode 325. Maximum Size Subarray Sum Equals k is rated Medium on LeetCode.
What is the time complexity of LeetCode 325. Maximum Size Subarray Sum Equals k?: The Python solution on this page runs in O(n).
What is the space complexity of LeetCode 325. Maximum Size Subarray Sum Equals k?: The Python solution on this page uses O(n), where n is the length of the array \textit{nums} auxiliary space.
What topics does LeetCode 325. Maximum Size Subarray Sum Equals k cover?: LeetCode 325. Maximum Size Subarray Sum Equals k is tagged Array, Hash Table and Prefix Sum on LeetCode.
Is LeetCode 325. Maximum Size Subarray Sum Equals k a premium problem?: Yes. LeetCode 325. Maximum Size Subarray Sum Equals k is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.