703.Kth Largest Element in a Stream
===

###### tags: `Easy`,`Tree`,`Heap`

[703. Kth Largest Element in a Stream](https://leetcode.com/problems/kth-largest-element-in-a-stream/)

### 題目描述

Design a class to find the k^th^ largest element in a stream. Note that it is the k^th^ largest element in the sorted order, not the k^th^ 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 k^th^ largest element in the stream.

### 範例

**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 k^th^ element.

### 解答
#### Python

class KthLargest:

    def __init__(self, k: int, nums: List[int]):
        self.k = k
        self.heap = []
        for num in nums:
            self.add(num)
        

    def add(self, val: int) -> int:
        if len(self.heap) < self.k:
            heapq.heappush(self.heap, val)
        elif val > self.heap[0]:
            heapq.heapreplace(self.heap, val)
        return self.heap[0]

> [name=Yen-Chi Chen][time=Tue, May 23, 2023]

class KthLargest:

    def __init__(self, k: int, nums: List[int]):
        self.k = k
        self.heap = nums
        heapq.heapify(self.heap)

        while len(self.heap) > self.k:
            heapq.heappop(self.heap)

    def add(self, val: int) -> int:
        heapq.heappush(self.heap, val)
        if len(self.heap) > self.k:
            heapq.heappop(self.heap)

        return self.heap[0]

> [name=Ron Chen][time=Tue, May 23, 2023]

#### Javascript

class KthLargest {
  constructor(k, nums) {
    this.k = k;
    this.nums = nums;
  }

  add(val) {
    this.nums.push(val);
    this.nums.sort((a, b) => b - a);
    return this.nums[this.k - 1];
  }
}

> 用sort也會過ㄏㄏ
> [name=Marsgoat][time=Tue, May 23, 2023]

class KthLargest {
  constructor(k, nums) {
    this.k = k;
    this.minHeap = new MinHeap();
    for (const num of nums) {
      this.add(num);
    }
  }

  add(val) {
    this.minHeap.push(val);
    if (this.minHeap.size() > this.k) {
      this.minHeap.pop();
    }

    return this.minHeap.top();
  }
}

> minHeap就不貼了，我直接讓chatGPT把我之前的maxHeap直接改寫成minHeap
> [name=Marsgoat][time=Tue, May 23, 2023]

#### C++

class KthLargest {
public:
    multiset<int> bst;
    int k;
    vector<int> nums;
    KthLargest(int k, vector<int>& nums) {
        this->k = k;
        for (int x : nums) {
            bst.insert(x);
        }
    }
    
    int add(int val) {
        bst.insert(val);
        auto it = bst.end();
        advance(it, -k);
        return *it;
    }
};

> [name=Jerry Wu][time=True, May23, 2023]

### Reference

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