留着备用。
Heap是一种满足特定性质的数组，如下：
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title></title> </head> <body> <textarea id="data-area" rows="25" cols="80" placeholder="paste your data here..."></textarea> <p><button id="run">run code</button></p> <script type="text/javascript"> let btn = document.querySelector("#run"); btn.addEventListener("click", handleClick); function handleClick() { let dataArea = document.querySelector('#data-area'); let data = dataArea.value; let arr = CommonUtil.handleData(data); // 样例输入：2 8 1 14 7 9 3 10 4 16 console.log('before:', arr); Heap.buildMaxHeap(arr); console.log('after:', arr); } </script> <script type="text/javascript"> class CommonUtil { static handleData(data) { let result = []; let digit = /-?d+/g; let match; while(match = digit.exec(data)) { result.push(Number(match[0])); } return result; } } </script> <script type="text/javascript"> class Heap { // 把数组A转化为最大堆 static buildMaxHeap(A) { A.unshift(undefined); // 便于后续的下标计算 A.heapSize = A.length - 1; // 实际多存了一个undefined for (let i = Math.floor(A.heapSize / 2); i >= 1; --i) { // 对所有非叶结点调用一次maxHeapify // 之所以下标从后往前，是因为maxHeapify假定调用结点的左右子树都已经为最大堆 // 单个元素（叶结点）很自然地是一个最大堆 Heap.maxHeapify(A, i); } } // 维护堆的性质 static maxHeapify(A, i) { let l = Heap.left(i); let r = Heap.right(i); let largest = i; // maxHeapify假定调用结点的左右子树都已经为最大堆 // 只是把调用结点i放到恰当的位置，以维护堆的性质 if (l <= A.heapSize && A[l] > A[i]) { largest = l; } if (r <= A.heapSize && A[r] > A[largest]) { largest = r; } if (largest != i) { A[largest] = A[i] + A[largest]; A[i] = A[largest] - A[i]; A[largest] = A[largest] - A[i]; Heap.maxHeapify(A, largest); } } static left(i) { return 2 * i; } static right(i) { return 2 * i + 1; } } </script> </body> </html>
