Problem :
Given an array of integers and a number K. Find the count of distinct elements in every window of size K in the array.
Example 1:
Input:
N = 7, K = 4
A[] = {1,2,1,3,4,2,3}
Output: 3 4 4 3
Explanation: Window 1 of size k = 4 is
1 2 1 3. Number of distinct elements in
this window are 3.
Window 2 of size k = 4 is 2 1 3 4. Number
of distinct elements in this window are 4.
Window 3 of size k = 4 is 1 3 4 2. Number
of distinct elements in this window are 4.
Window 4 of size k = 4 is 3 4 2 3. Number
of distinct elements in this window are 3.
Example 2:
Input:
N = 3, K = 2
A[] = {4,1,1}
Output: 2 1
Your Task:
Your task is to complete the function countDistinct() which takes the array A[], the size of the array(N) and the window size(K) as inputs and returns an array containing the count of distinct elements in every contiguous window of size K in the array A[].
Expected Time Complexity: O(N).
Expected Auxiliary Space: O(N).Solution:
class Solution{
public:
vector <int> countDistinct (int A[], int n, int k)
{
//code here.
vector<int> ret;
map<int, int> mp;
for(int i=0; i<n; i++) {
if(i>=k){
if(--mp[A[i-k]] == 0){
mp.erase(A[i-k]);
}
}
mp[A[i]]++;
if(i>=k-1){
ret.push_back(mp.size());
}
}
return ret;
}
};