Feat: 힙 골드 4 카드 정렬하기

Author: ienrum

Diff for: 5주차/채수혁/골드4__카드_정렬하기.js

@@ -0,0 +1,122 @@
+const local_input = `
+4
+2
+2
+3
+3
+`;
+
+const input = process.execArgv.includes("--stack-size=65536")
+  ? require("fs").readFileSync("dev/stdin").toString()
+  : local_input;
+
+const inputs = input
+  .trim()
+  .split("\n")
+  .map((v) => Number(v));
+
+const n = inputs[0];
+const arr = inputs.slice(1);
+
+// 최소힙 구현
+class MinHeap {
+  constructor() {
+    this.heap = [];
+  }
+
+  insert(value) {
+    this.heap.push(value);
+    this.heapifyUp();
+  }
+
+  heapifyUp() {
+    let index = this.heap.length - 1;
+    while (index > 0) {
+      let parentIndex = Math.floor((index - 1) / 2);
+
+      if (this.heap[parentIndex] <= this.heap[index]) {
+        break;
+      }
+
+      [this.heap[parentIndex], this.heap[index]] = [
+        this.heap[index],
+        this.heap[parentIndex],
+      ];
+      index = parentIndex;
+    }
+  }
+
+  extractMin() {
+    const min = this.heap[0];
+    const ok = this.heap.pop();
+    if (this.size() !== 0) this.heap[0] = ok;
+    this.heapifyDown();
+    return min;
+  }
+
+  heapifyDown(index = 0) {
+    let leftChildIndex = 2 * index + 1;
+    let rightChildIndex = 2 * index + 2;
+    let smallest = index;
+
+    if (
+      leftChildIndex < this.heap.length &&
+      this.heap[leftChildIndex] < this.heap[smallest]
+    ) {
+      smallest = leftChildIndex;
+    }
+
+    if (
+      rightChildIndex < this.heap.length &&
+      this.heap[rightChildIndex] < this.heap[smallest]
+    ) {
+      smallest = rightChildIndex;
+    }
+
+    if (smallest !== index) {
+      [this.heap[smallest], this.heap[index]] = [
+        this.heap[index],
+        this.heap[smallest],
+      ];
+      this.heapifyDown(smallest);
+    }
+  }
+  size() {
+    return this.heap.length;
+  }
+  peek() {
+    return this.heap[0];
+  }
+}
+
+const main = () => {
+  // n이 1이면 0을 출력하고 종료
+  if (n === 1) {
+    console.log(0);
+    return;
+  }
+  const minHeap = new MinHeap();
+
+  const result = [];
+
+  // 최소힙에 모든 원소를 삽입
+  arr.forEach((v) => minHeap.insert(v));
+
+  let prev = minHeap.extractMin() + minHeap.extractMin();
+  result.push(prev);
+
+  // 힙의 크기가 1이 될 때까지 반복
+  while (minHeap.size() > 0) {
+    // 힙에서 가장 작은 두 개의 원소를 꺼내서 더한 후 다시 삽입
+    minHeap.insert(prev);
+    prev = minHeap.extractMin() + minHeap.extractMin();
+
+    // 더한 값을 결과 배열에 삽입
+    result.push(prev);
+  }
+
+  // 모든 원소를 더한 값을 출력
+  console.log(result.reduce((acc, v) => acc + v, 0));
+};
+
+main();