Question Definition
Given a list of non-negative numbers and a target integer k, write a function to check if the array has a continuous subarray of size at least 2 that sums up to the multiple of k, that is, sums up to n*k where n is also an integer.
Example 1:
Input: [23, 2, 4, 6, 7], k=6
Output: True
Explanation: Because [2, 4] is a continuous subarray of size 2 and sums up to 6.
Example 2:
Input: [23, 2, 6, 4, 7], k=6
Output: True
Explanation: Because [23, 2, 6, 4, 7] is an continuous subarray of size 5 and sums up to 42.
Note: The length of the array won’t exceed 10,000. You may assume the sum of all the numbers is in the range of a signed 32-bit integer.
Java Solution
public boolean checkSubarraySum(int[] nums, int k) {
if(nums.length == 0)
return false;
int[] sum = new int[nums.length];
sum[0] = nums[0];
for(int i = 1; i < nums.length; i++)
sum[i] = nums[i] + sum[i - 1];
for(int i = 1; i < nums.length; i++){
if((k == 0 && sum[i] == 0) || (k != 0 && sum[i] % k == 0))
return true;
for(int j = 0; j < i - 1; j++){
if((k == 0 && (sum[i] - sum[j]) == 0) || (k != 0 && (sum[i] - sum[j]) % k == 0))
return true;
}
}
return false;
}
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