Created
January 16, 2026 15:26
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Heap
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| function heapify(tree, n, i) { | |
| let min = i; | |
| let l = 2 * i + 1; | |
| let r = 2 * i + 2; | |
| if (l < n && tree[l] < tree[min]) { | |
| min = l; | |
| } | |
| if (r < n && tree[r] < tree[min]) { | |
| min = r; | |
| } | |
| if (min !== i) { | |
| [tree[i], tree[min]] = [tree[min], tree[i]]; | |
| heapify(tree, n, min); | |
| } | |
| } | |
| function buildHeap(tree) { | |
| let n = tree.length; | |
| let startIdx = Math.floor(n / 2) - 1; | |
| for (let i = startIdx; i >= 0; i--) { | |
| heapify(tree, n, i); | |
| } | |
| } | |
| function addHeap(tree, newItem) { | |
| tree.push(newItem); | |
| let idx = tree.length - 1; | |
| while (idx > 0) { | |
| let parentIdx = Math.floor((idx - 1) / 2); | |
| if (tree[idx] >= tree[parentIdx]) break; | |
| [tree[idx], tree[parentIdx]] = [tree[parentIdx], tree[idx]]; | |
| idx = parentIdx; | |
| } | |
| } | |
| function deleteHeap(tree, idx = 0) { | |
| if (tree.length === 0) return; | |
| tree[idx] = tree[tree.length - 1]; | |
| tree.pop(); | |
| heapify(tree, tree.length, idx); | |
| } | |
| // ================= TEST ================= | |
| let aTree = [10, 7, 6, 1, 4, 3, 9, 0, 15]; | |
| console.log("origin:", aTree); | |
| buildHeap(aTree); | |
| console.log("heap:", aTree); | |
| console.log("add -2"); | |
| addHeap(aTree, -2); | |
| console.log(aTree); | |
| console.log("delete min"); | |
| deleteHeap(aTree); | |
| console.log(aTree); |
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