LeetCode in Kotlin
992. Subarrays with K Different Integers
Hard
Given an integer array nums and an integer k, return the number of good subarrays of nums.
A good array is an array where the number of different integers in that array is exactly k.
- For example,
[1,2,3,1,2]has3different integers:1,2, and3.
A subarray is a contiguous part of an array.
Example 1:
Input: nums = [1,2,1,2,3], k = 2
Output: 7
Explanation: Subarrays formed with exactly 2 different integers: [1,2], [2,1], [1,2], [2,3], [1,2,1], [2,1,2], [1,2,1,2]
Example 2:
Input: nums = [1,2,1,3,4], k = 3
Output: 3
Explanation: Subarrays formed with exactly 3 different integers: [1,2,1,3], [2,1,3], [1,3,4].
Constraints:
1 <= nums.length <= 2 * 1041 <= nums[i], k <= nums.length
Solution
class Solution {
fun subarraysWithKDistinct(nums: IntArray, k: Int): Int {
var res = 0
var prefix = 0
val cnt = IntArray(nums.size + 1)
var i = 0
var j = 0
var uniqueCount = 0
while (i < nums.size) {
if (cnt[nums[i]]++ == 0) {
uniqueCount++
}
if (uniqueCount > k) {
--cnt[nums[j++]]
prefix = 0
uniqueCount--
}
while (cnt[nums[j]] > 1) {
++prefix
--cnt[nums[j++]]
}
if (uniqueCount == k) {
res += prefix + 1
}
i++
}
return res
}
}