ContinuousSubarraySum523.kt

package medium

/**
 * Given an integer array nums and an integer k, return true if nums has a continuous subarray of size at least two whose elements sum up to a multiple of k, or false otherwise.

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
 */
fun checkSubarraySum(nums: IntArray, k: Int): Boolean {
    val map =HashMap<Int,Int>()
    map[0]=0
    var sum=0
    for(i in nums.indices)
    {
        sum+=nums[i]
        if(!map.containsKey(sum%k))
            map[sum%k]=i+1
        else if(map.getOrDefault(sum%k,nums.size+1)<i)
            return true
    }
    return false
}