Merge pull request #3382 from arkadiusz-wrzawinski/typescript-0703-kth-largest-element-in-a-stream

Create 0703-kth-largest-element-in-a-stream.ts

Author: Ykhan799

Diff for: typescript/0703-kth-largest-element-in-a-stream.ts

@@ -0,0 +1,61 @@
+class KthLargest {
+    backingArray: number[];
+    size: number;
+
+    constructor(k: number, nums: number[]) {
+        this.backingArray = [];
+        this.size = k;
+        for(const num of nums) this.add(num)
+    }
+
+    add(val: number): number {
+        const newLength = this.backingArray.push(val)
+        this.shiftUp(newLength - 1);
+
+        if (newLength > this.size) this.pop();
+
+        return this.backingArray[0];
+    }
+
+    private pop() {
+        this.swap(0, this.backingArray.length - 1)
+        this.backingArray.length -= 1;
+        this.shiftDown(0)
+    }
+
+    private shiftDown(elementIndex: number) {
+        let leftChildIndex = elementIndex * 2 + 1;
+        let rightChildIndex = elementIndex * 2 + 2;
+
+        while ((leftChildIndex < this.backingArray.length && this.backingArray[leftChildIndex] < this.backingArray[elementIndex])
+        || (rightChildIndex < this.backingArray.length && this.backingArray[rightChildIndex] < this.backingArray[elementIndex])) {
+            let smallestIndex = leftChildIndex;
+            if (rightChildIndex < this.backingArray.length && this.backingArray[rightChildIndex] < this.backingArray[smallestIndex]) {
+                smallestIndex = rightChildIndex
+            }
+
+            this.swap(elementIndex, smallestIndex);
+
+            elementIndex = smallestIndex;
+            leftChildIndex = elementIndex * 2 + 1;
+            rightChildIndex = elementIndex * 2 + 2;
+        }
+    }
+
+    private shiftUp(elementIndex: number) {
+        if (elementIndex === 0) return;
+
+        let parentIndex = Math.floor((elementIndex - 1) / 2);
+        while (this.backingArray[parentIndex] > this.backingArray[elementIndex]) {
+            this.swap(elementIndex, parentIndex);
+            elementIndex = parentIndex;
+            parentIndex = Math.floor((elementIndex - 1) / 2);
+        }
+    }
+
+    private swap(indexA: number, indexB: number) {
+        const temp = this.backingArray[indexA];
+        this.backingArray[indexA] = this.backingArray[indexB];
+        this.backingArray[indexB] = temp;
+    }
+}