2395. Find Subarrays With Equal Sum
Description
Given a 0-indexed integer array nums
, determine whether there exist two subarrays of length 2
with equal sum. Note that the two subarrays must begin at different indices.
Return true
if these subarrays exist, and false
otherwise.
A subarray is a contiguous non-empty sequence of elements within an array.
Example 1:
Input: nums = [4,2,4] Output: true Explanation: The subarrays with elements [4,2] and [2,4] have the same sum of 6.
Example 2:
Input: nums = [1,2,3,4,5] Output: false Explanation: No two subarrays of size 2 have the same sum.
Example 3:
Input: nums = [0,0,0] Output: true Explanation: The subarrays [nums[0],nums[1]] and [nums[1],nums[2]] have the same sum of 0. Note that even though the subarrays have the same content, the two subarrays are considered different because they are in different positions in the original array.
Constraints:
2 <= nums.length <= 1000
-109 <= nums[i] <= 109
Solutions
Solution 1: Hash Table
We can traverse the array $nums$, and use a hash table $vis$ to record the sum of every two adjacent elements in the array. If the sum of the current two elements has already appeared in the hash table, then return true
. Otherwise, add the sum of the current two elements to the hash table.
If we finish traversing and haven't found two subarrays that meet the condition, return false
.
The time complexity is $O(n)$, and the space complexity is $O(n)$, where $n$ is the length of the array $nums$.
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