66 lines
2.5 KiB
C++
66 lines
2.5 KiB
C++
//
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// Created by maximilian on 16.04.22.
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//
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#include <cassert>
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#include <bit>
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#include "segment_tree.h"
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SegmentTree::SegmentTree(const std::vector<RectCoord> &coords):
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_nodes() {
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assert(!coords.empty());
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// reserve nodes for a full binary tree with at least as many leaves as intervals
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size_t num_leaf_nodes = coords.size() -1;
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size_t num_meta_nodes = std::bit_ceil(num_leaf_nodes) - 1;
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// Initialize all nodes with zero coverage and dummy interval
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_nodes.resize(2 * num_meta_nodes + 1, {0, coords[num_leaf_nodes].coord, coords[num_leaf_nodes].coord, 0});
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// We initialize the tree from bottom up, keeping track of the index ranges
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// and the length of the corresponding segment
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for(Index leaf_node_idx = 0 ; leaf_node_idx < num_leaf_nodes ; ++leaf_node_idx) {
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_nodes[leaf_node_idx + num_meta_nodes].left_coord = coords[leaf_node_idx].coord;
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_nodes[leaf_node_idx + num_meta_nodes].right_coord = coords[leaf_node_idx +1].coord;
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}
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// Note that there are remaining leafs that represent dummy ranges
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for(Index node_idx = num_meta_nodes - 1; node_idx != -1 ; --node_idx) {
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_nodes[node_idx].left_coord = left_child(node_idx).left_coord;
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_nodes[node_idx].right_coord = right_child(node_idx).right_coord;
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}
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assert(_nodes.front().left_coord == coords.front().coord);
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assert(_nodes.front().right_coord == coords.back().coord);
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assert(_nodes.front().segment_length() == coords.back().coord - coords.front().coord);
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}
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void SegmentTree::add_interval(Interval interval, Index node_idx) {
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if (interval.left <= _nodes[node_idx].left_coord && _nodes[node_idx].right_coord <= interval.right) {
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add_coverage(node_idx);
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} else {
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if(interval.left < left_child(node_idx).right_coord) {
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add_interval(interval, left_child_idx(node_idx));
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}
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if(right_child(node_idx).left_coord < interval.right) {
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add_interval(interval, right_child_idx(node_idx));
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}
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update_covered_length(node_idx);
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}
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}
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void SegmentTree::remove_interval(Interval interval, Index node_idx) {
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if (interval.left <= _nodes[node_idx].left_coord && _nodes[node_idx].right_coord <= interval.right) {
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remove_coverage(node_idx);
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} else {
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if(interval.left < left_child(node_idx).right_coord) {
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remove_interval(interval, left_child_idx(node_idx));
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}
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if(right_child(node_idx).left_coord < interval.right) {
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remove_interval(interval, right_child_idx(node_idx));
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}
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}
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}
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