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Merge branch 'DaleStudy:main' into main
2 parents 21d8ac7 + a68c8a4 commit 245aa4c

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β€Žfind-median-from-data-stream/HoonDongKang.ts

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/**
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* [Problem]: [295] Find Median from Data Stream
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* (https://leetcode.com/problems/find-median-from-data-stream/description/)
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*/
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class Heap {
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private numbers: number[];
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private compare: (a: number, b: number) => boolean;
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constructor(compare: (a: number, b: number) => boolean) {
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this.numbers = [];
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this.compare = compare;
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}
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private getParentIdx(index: number) {
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return Math.floor((index - 1) / 2);
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}
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private getLeftChildIdx(index: number) {
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return 2 * index + 1;
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}
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private getRightChildIdx(index: number) {
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return 2 * index + 2;
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}
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private swap(index1: number, index2: number): void {
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[this.numbers[index1], this.numbers[index2]] = [this.numbers[index2], this.numbers[index1]];
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}
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private heapifyUp(index: number) {
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const parentIndex = this.getParentIdx(index);
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if (0 <= parentIndex && this.compare(this.numbers[index], this.numbers[parentIndex])) {
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this.swap(index, parentIndex);
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this.heapifyUp(parentIndex);
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}
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}
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private heapifyDown(index: number): void {
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const leftChildIndex = this.getLeftChildIdx(index);
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const rightChildIndex = this.getRightChildIdx(index);
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let largestIndex = index;
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if (
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leftChildIndex < this.numbers.length &&
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this.compare(this.numbers[leftChildIndex], this.numbers[largestIndex])
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) {
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largestIndex = leftChildIndex;
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}
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if (
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rightChildIndex < this.numbers.length &&
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this.compare(this.numbers[rightChildIndex], this.numbers[largestIndex])
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) {
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largestIndex = rightChildIndex;
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}
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if (largestIndex !== index) {
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this.swap(index, largestIndex);
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this.heapifyDown(largestIndex);
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}
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}
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insert(number: number) {
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this.numbers.push(number);
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this.heapifyUp(this.numbers.length - 1);
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}
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pop() {
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if (this.numbers.length === 0) {
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return null;
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}
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if (this.numbers.length === 1) {
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return this.numbers.pop()!;
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}
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const root = this.numbers[0];
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this.numbers[0] = this.numbers.pop()!;
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this.heapifyDown(0);
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return root;
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}
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peek() {
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return this.numbers.length > 0 ? this.numbers[0] : null;
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}
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size(): number {
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return this.numbers.length;
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}
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}
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class MedianFinder {
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private smallHeap: Heap;
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private largeHeap: Heap;
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constructor() {
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this.smallHeap = new Heap((a, b) => a > b);
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this.largeHeap = new Heap((a, b) => a < b);
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}
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//μ‹œκ°„λ³΅μž‘λ„ O(log n)
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addNum(num: number): void {
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this.smallHeap.insert(num);
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this.largeHeap.insert(this.smallHeap.pop()!);
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if (this.smallHeap.size() < this.largeHeap.size()) {
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this.smallHeap.insert(this.largeHeap.pop()!);
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}
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}
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//μ‹œκ°„λ³΅μž‘λ„ O(1)
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findMedian(): number {
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if (this.smallHeap.size() > this.largeHeap.size()) {
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return this.smallHeap.peek()!;
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} else {
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return (this.smallHeap.peek()! + this.largeHeap.peek()!) / 2;
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}
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}
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}
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/**
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* Your MedianFinder object will be instantiated and called as such:
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* var obj = new MedianFinder()
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* obj.addNum(num)
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* var param_2 = obj.findMedian()
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*/

β€Žfind-median-from-data-stream/Jeehay28.ts

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class MedianFinder {
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// [1, 2, 3, 4, 5, 6]
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private lower: MaxHeap; // max heap [3, 2, 1]
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private upper: MinHeap; // min heap [4, 5, 6]
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constructor() {
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this.upper = new MinHeap();
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this.lower = new MaxHeap();
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}
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// TC: O(log n)
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// SC: O(n)
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addNum(num: number): void {
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if (this.upper.size() === 0 || this.upper.getRoot() <= num) {
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this.upper.insert(num);
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} else {
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this.lower.insert(num);
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}
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// Balance
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if (this.lower.size() - this.upper.size() > 1) {
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this.upper.insert(this.lower.removeRoot());
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} else if (this.upper.size() - this.lower.size() > 1) {
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this.lower.insert(this.upper.removeRoot());
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}
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}
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// TC: O(1)
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// SC: O(1)
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findMedian(): number {
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if (this.upper.size() === this.lower.size()) {
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return (this.upper.getRoot() + this.lower.getRoot()) / 2;
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} else if (this.upper.size() > this.lower.size()) {
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return this.upper.getRoot();
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} else {
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return this.lower.getRoot();
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}
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}
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}
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/**
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* Your MedianFinder object will be instantiated and called as such:
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* var obj = new MedianFinder()
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* obj.addNum(num)
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* var param_2 = obj.findMedian()
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*/
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class MinHeap {
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private heap: number[] = [];
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size(): number {
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return this.heap.length;
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}
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getRoot(): number {
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return this.heap[0];
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}
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insert(num: number): void {
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this.heap.push(num);
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this.bubbleUp();
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}
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removeRoot(): number {
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const top = this.heap[0];
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const end = this.heap.pop()!;
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if (this.heap.length > 0) {
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this.heap[0] = end;
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this.bubbleDown();
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}
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return top;
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}
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// Fix after removal (downward)
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bubbleDown(): void {
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let idx = 0;
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const length = this.heap.length;
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const val = this.heap[0];
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while (true) {
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let leftIdx = 2 * idx + 1;
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let rightIdx = 2 * idx + 2;
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let swap = idx;
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if (leftIdx < length && this.heap[leftIdx] < this.heap[swap]) {
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swap = leftIdx;
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}
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if (rightIdx < length && this.heap[rightIdx] < this.heap[swap]) {
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swap = rightIdx;
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}
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if (swap === idx) break;
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this.heap[idx] = this.heap[swap];
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this.heap[swap] = val;
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idx = swap;
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}
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}
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// Fix after insert (upward)
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bubbleUp(): void {
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let idx = this.heap.length - 1;
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const val = this.heap[idx];
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// Heap as an array
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// left child: 2 * i + 1
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// right child: 2 * i + 2
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// parent: Math.floor((i-1) / 2)
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while (idx > 0) {
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const parentIdx = Math.floor((idx - 1) / 2);
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const parent = this.heap[parentIdx];
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if (val >= parent) break;
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this.heap[parentIdx] = val;
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this.heap[idx] = parent;
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idx = parentIdx;
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}
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}
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}
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class MaxHeap {
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private heap: number[] = [];
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size(): number {
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return this.heap.length;
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}
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getRoot(): number {
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return this.heap[0];
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}
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insert(num: number): void {
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this.heap.push(num);
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this.bubbleUp();
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}
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removeRoot(): number {
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const top = this.heap[0];
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const end = this.heap.pop()!;
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if (this.heap.length > 0) {
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this.heap[0] = end;
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this.bubbleDown();
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}
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return top;
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}
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bubbleDown(): void {
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let idx = 0;
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const length = this.heap.length;
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const val = this.heap[0];
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while (true) {
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let leftIdx = 2 * idx + 1;
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let rightIdx = 2 * idx + 2;
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let swap = idx;
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if (leftIdx < length && this.heap[leftIdx] > this.heap[swap]) {
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swap = leftIdx;
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}
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if (rightIdx < length && this.heap[rightIdx] > this.heap[swap]) {
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swap = rightIdx;
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}
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if (swap === idx) break;
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this.heap[idx] = this.heap[swap];
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this.heap[swap] = val;
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idx = swap;
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}
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}
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bubbleUp(): void {
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let idx = this.heap.length - 1;
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const val = this.heap[idx];
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while (idx > 0) {
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const parentIdx = Math.floor((idx - 1) / 2);
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const parent = this.heap[parentIdx];
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if (val <= parent) break;
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this.heap[parentIdx] = val;
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this.heap[idx] = parent;
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idx = parentIdx;
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}
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}
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}

β€Žfind-median-from-data-stream/printjin-gmailcom.py

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import heapq
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class MedianFinder:
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def __init__(self):
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self.low = []
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self.high = []
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def addNum(self, num):
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heapq.heappush(self.low, -num)
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heapq.heappush(self.high, -heapq.heappop(self.low))
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if len(self.high) > len(self.low):
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heapq.heappush(self.low, -heapq.heappop(self.high))
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def findMedian(self):
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if len(self.low) > len(self.high):
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return -self.low[0]
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return (-self.low[0] + self.high[0]) / 2

β€Žfind-median-from-data-stream/yyyyyyyyyKim.py

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class MedianFinder:
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# Follow up : 두 개의 heap μ‚¬μš©ν•΄μ„œ κ΅¬ν˜„ κ°€λŠ₯(μ‹œκ°„λ³΅μž‘λ„ O(log n), μΆ”κ°€ 곡뢀 ν•„μš”ν•¨)
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# heap μ‚¬μš©ν•˜μ§€ μ•Šκ³  이진 탐색 μ‚½μž…μœΌλ‘œ ν’€μ—ˆμŒ
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def __init__(self):
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# 숫자 μ €μž₯ν•  리슀트 생성
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self.arr = []
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def addNum(self, num: int) -> None:
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# 숫자 μΆ”κ°€ν•˜κ³  μ •λ ¬ν•˜κΈ°
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# self.arr.append(num)
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# self.arr.sort() -> μ‹œκ°„μ΄ˆκ³Ό(μ‹œκ°„λ³΅μž‘λ„ O(n log n))
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# μ΄μ§„νƒμƒ‰μ‚½μž…(μ‹œκ°„λ³΅μž‘λ„ O(n))
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bisect.insort(self.arr, num)
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def findMedian(self) -> float:
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# 길이가 ν™€μˆ˜λ©΄ κ°€μš΄λ° κ°’ 리턴
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if len(self.arr)%2 == 1:
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return self.arr[len(self.arr)//2]
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# 길이가 짝수면 κ°€μš΄λ° 두 수의 평균 리턴
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return (self.arr[len(self.arr)//2-1] + self.arr[len(self.arr)//2]) / 2
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# Your MedianFinder object will be instantiated and called as such:
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# obj = MedianFinder()
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# obj.addNum(num)
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# param_2 = obj.findMedian()

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