Created
March 8, 2024 16:16
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MaxHeap Ruby implementation
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| class MaxHeap | |
| def initialize | |
| @heap = [] | |
| end | |
| def push(val) | |
| @heap << val | |
| sift_up(@heap.size - 1) | |
| end | |
| def pop | |
| return @heap.pop if @heap.size <= 1 | |
| max = @heap.first | |
| @heap[0] = @heap.pop | |
| sift_down(0) | |
| max | |
| end | |
| private | |
| def sift_up(index) | |
| return if index <= 0 | |
| parent_index = (index - 1) / 2 | |
| return if @heap[parent_index] >= @heap[index] | |
| @heap[parent_index], @heap[index] = @heap[index], @heap[parent_index] | |
| sift_up(parent_index) | |
| end | |
| def sift_down(index) | |
| left_child_index = 2 * index + 1 | |
| right_child_index = 2 * index + 2 | |
| max_index = index | |
| if left_child_index < @heap.size && @heap[left_child_index] > @heap[max_index] | |
| max_index = left_child_index | |
| end | |
| if right_child_index < @heap.size && @heap[right_child_index] > @heap[max_index] | |
| max_index = right_child_index | |
| end | |
| if max_index != index | |
| @heap[index], @heap[max_index] = @heap[max_index], @heap[index] | |
| sift_down(max_index) | |
| end | |
| end | |
| end |
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