Today I have done leetcode's April LeetCoding Challenge with cpp.

April LeetCoding Challenge 8

Description

Kth Largest Element in a Stream

Design a class to find the kth largest element in a stream. Note that it is the kth largest element in the sorted order, not the kth distinct element.

Implement KthLargest class:

• KthLargest(int k, int[] nums) Initializes the object with the integer k and the stream of integers nums.
• int add(int val) Appends the integer val to the stream and returns the element representing the kth largest element in the stream.

Example 1:

Input
["KthLargest", "add", "add", "add", "add", "add"]
[[3, [4, 5, 8, 2]], [3], [5], [10], [9], [4]]
Output
[null, 4, 5, 5, 8, 8]

Explanation
KthLargest kthLargest = new KthLargest(3, [4, 5, 8, 2]);
kthLargest.add(3);   // return 4
kthLargest.add(5);   // return 5
kthLargest.add(10);  // return 5
kthLargest.add(9);   // return 8
kthLargest.add(4);   // return 8

Constraints:

• 1 <= k <= 10^4
• 0 <= nums.length <= 10^4
• -10^4 <= nums[i] <= 10^4
• -10^4 <= val <= 10^4
• At most 10^4 calls will be made to add.
• It is guaranteed that there will be at least k elements in the array when you search for the kth element.

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class KthLargest {
  priority_queue<int, vector<int>, greater<int>> pq;
public:
  KthLargest(int k, vector<int>& nums) {
    int len = nums.size();
    for(int i = 0; i < len && i < k; ++i) {
      pq.push(nums[i]);
    }
    for(int i = k; i < len; ++i) {
      pq.push(nums[i]);
      pq.pop();
    }
    if(len < k) pq.push(INT_MIN);
  }
  
  int add(int val) {
    pq.push(val);
    pq.pop();
    return pq.top();
  }
};

// Accepted
// 10/10 cases passed (20 ms)
// Your runtime beats 99.9 % of cpp submissions
// Your memory usage beats 17.93 % of cpp submissions (19.9 MB)