LeetCode 523. Continuous Subarray Sum

Given an integer array nums and an integer k, return true if nums has a good subarray or false otherwise.

A good subarray is a subarray where:

• its length is at least two, and

• the sum of the elements of the subarray is a multiple of k.

Note that:

• A subarray is a contiguous part of the array.

• An integer x is a multiple of k if there exists an integer n such that x = n * k. 0 is always a multiple of k.

Example 1:

Input: nums = [23,2,4,6,7], k = 6

Output: true

Explanation: [2, 4] is a continuous subarray of size 2 whose elements sum up to 6.

Example 2:

Input: nums = [23,2,6,4,7], k = 6

Output: true

Explanation: [23, 2, 6, 4, 7] is an continuous subarray of size 5 whose elements sum up to 42. 42 is a multiple of 6 because 42 = 7 * 6 and 7 is an integer.

Example 3:

Input: nums = [23,2,6,4,7], k = 13

Output: false

Constraints:

• 1 <= nums.length <= 105

• 0 <= nums[i] <= 109

• 0 <= sum(nums[i]) <= 231 - 1

• 1 <= k <= 231 - 1

• 每次用map去存储这个余数对应的位置，如果存在i-对应的位置大于1，说明是超过2个的，这时候返回true即可，剩下的情况就是返回false了；

• 下面是代码：

Runtime: 21 ms, faster than 80.19% of Java online submissions for Continuous Subarray Sum.

Memory Usage: 51.7 MB, less than 62.16% of Java online submissions for Continuous Subarray Sum.