Created
March 15, 2023 18:48
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MinHeap
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| package main | |
| import ( | |
| "fmt" | |
| "math" | |
| ) | |
| func parent(i int) int { | |
| return (i - 1) / 2 | |
| } | |
| func left(i int) int { | |
| return (2 * i) + 1 | |
| } | |
| func right(i int) int { | |
| return (2 * i) + 2 | |
| } | |
| type minheap struct { | |
| heap []int | |
| } | |
| func (h *minheap) swap(i, j int) { | |
| h.heap[i], h.heap[j] = h.heap[j], h.heap[i] | |
| } | |
| func (h *minheap) insert(val int) { | |
| h.heap = append(h.heap, val) | |
| h.heapifyUp(len(h.heap) - 1) | |
| } | |
| func (h *minheap) delete(val int) { | |
| lidx := len(h.heap) - 1 | |
| for i := 0; i <= lidx; i += 1 { | |
| if h.heap[i] == val { | |
| h.heap[i] = h.heap[lidx] | |
| h.heap = h.heap[:lidx] | |
| h.heapifyDown(i) | |
| break | |
| } | |
| } | |
| } | |
| func (h *minheap) getmin() int { | |
| return h.heap[0] | |
| } | |
| func (h *minheap) deletemin() int { | |
| lidx := len(h.heap) - 1 | |
| temp := 0 | |
| temp, h.heap[0] = h.heap[0], h.heap[lidx] | |
| h.heap = h.heap[:lidx] | |
| h.heapifyDown(0) | |
| return temp | |
| } | |
| func (h *minheap) decreasekey(key, sub int) { | |
| lidx := len(h.heap) - 1 | |
| for i := 0; i <= lidx; i += 1 { | |
| if h.heap[i] == key { | |
| h.heap[i] = h.heap[i] - sub | |
| if i > 0 && h.heap[i] < h.heap[parent(i)] { | |
| h.heapifyUp(i) | |
| } else { | |
| h.heapifyDown(i) | |
| } | |
| break | |
| } | |
| } | |
| } | |
| func (h *minheap) print() { | |
| fmt.Println(h.heap) | |
| } | |
| func (h *minheap) heapifyUp(idx int) { | |
| for h.heap[parent(idx)] > h.heap[idx] { | |
| h.swap(parent(idx), idx) | |
| idx = parent(idx) | |
| } | |
| } | |
| func (h *minheap) heapifyDown(idx int) { | |
| lheap := len(h.heap) | |
| for idx < len(h.heap) { | |
| lidx, ridx := left(idx), right(idx) | |
| if lidx < lheap && h.heap[lidx] < h.heap[idx] { | |
| idx = lidx | |
| } | |
| if ridx < lheap && h.heap[ridx] < h.heap[idx] { | |
| idx = ridx | |
| } | |
| if h.heap[parent(idx)] > h.heap[idx] { | |
| h.swap(parent(idx), idx) | |
| } else { | |
| break | |
| } | |
| } | |
| } | |
| func (h *minheap) height() int { | |
| hlen := len(h.heap) | |
| if hlen != 0 { | |
| return int(math.Floor(math.Log2(float64(hlen)))) + 1 | |
| } | |
| return 0 | |
| } | |
| func main() { | |
| tree := &minheap{ | |
| heap: make([]int, 0), | |
| } | |
| // insert | |
| tree.insert(2) | |
| tree.insert(12) | |
| tree.insert(1) | |
| tree.insert(-2) | |
| tree.insert(23) | |
| tree.insert(-7) | |
| tree.insert(5) | |
| tree.insert(22) | |
| tree.print() | |
| // delete | |
| tree.delete(23) | |
| tree.print() | |
| // sub | |
| tree.decreasekey(22, 22) | |
| tree.print() | |
| // sub | |
| tree.decreasekey(-2, -5) | |
| tree.print() | |
| // get min | |
| fmt.Println(tree.getmin()) | |
| fmt.Println(tree.deletemin()) | |
| fmt.Println(tree.getmin()) | |
| } |
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