Kth Largest Numbers From Stream - Amazon Top Interview Questions
Problem Statement :
Implement a data structure with the following methods: KthLargestStream(int[] nums, int k) which constructs the instance. int add(int val) which adds val to nums and returns the k (0-indexed) largest value in nums Constraints 1 ≤ n ≤ 100,000 where n is the length of nums 0 ≤ m ≤ 100,000 where m is the number of calls to add k + 1 ≤ n Example 1 Input methods = ["constructor", "add", "add", "add", "add"] arguments = [[[1, 2, 4, 3], 3], [5], [6], [7], [8]]` Output [None, 2, 3, 4, 5] Explanation s = KthLargestStream([1,2,4,3],3) s.add(5) == 2 # Stream has [1, 2, 3, 4, 5] s.add(6) == 3 # Stream has [1, 2, 3, 4, 5, 6] s.add(7) == 4 # Stream has [1, 2, 3, 4, 5, 6, 7] s.add(8) == 5 # Stream has [1, 2, 3, 4, 5, 6, 7, 8]
Solution :
Solution in C++ :
class KthLargestStream {
public:
KthLargestStream(vector<int>& nums, int k) {
K = k + 1;
for (auto& num : nums) {
pq.push(num);
if (pq.size() > K) {
pq.pop();
}
}
}
int add(int val) {
pq.push(val);
if (pq.size() > K) {
pq.pop();
}
return pq.top();
}
private:
priority_queue<int, vector<int>, greater<int>> pq;
int K;
};
Solution in Java :
import java.util.*;
class KthLargestStream {
PriorityQueue<Integer> pq;
int k;
public KthLargestStream(int[] nums, int k) {
this.pq = new PriorityQueue<Integer>();
this.k = k;
for (int num : nums) {
pq.add(num);
if (pq.size() > k + 1)
pq.poll();
}
}
public int add(int val) {
pq.add(val);
if (pq.size() > k + 1)
pq.poll();
return pq.peek();
}
}
Solution in Python :
class KthLargestStream:
def __init__(self, nums, k):
heapq.heapify(nums)
while len(nums) > k + 1:
heapq.heappop(nums)
self.nums = nums
def add(self, val):
heapq.heappushpop(self.nums, val)
return self.nums[0]
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