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implement segment tree with stack directly

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Maximilian Keßler 2022-04-17 13:38:52 +02:00
parent 279ca3bd14
commit a0f3b12ece
2 changed files with 54 additions and 36 deletions
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41
segment_tree.cpp
View file

@ -3,6 +3,7 @@
// //
#include <cassert> #include <cassert>
#include <bit> #include <bit>
#include <stack>
#include "segment_tree.h" #include "segment_tree.h"
SegmentTree::SegmentTree(const std::vector<RectCoord> &coords): SegmentTree::SegmentTree(const std::vector<RectCoord> &coords):
@ -33,30 +34,54 @@ SegmentTree::SegmentTree(const std::vector<RectCoord> &coords):
assert(_nodes.front().segment_length() == coords.back().coord - coords.front().coord); assert(_nodes.front().segment_length() == coords.back().coord - coords.front().coord);
} }
void SegmentTree::add_interval(Interval interval, Index node_idx) { void SegmentTree::add_interval(Interval interval) {
std::stack<Index> visit_to;
std::vector<Index> update_to;
visit_to.push(0);
while(!visit_to.empty()) {
Index node_idx = visit_to.top();
visit_to.pop();
if (interval.left <= _nodes[node_idx].left_coord && _nodes[node_idx].right_coord <= interval.right) { if (interval.left <= _nodes[node_idx].left_coord && _nodes[node_idx].right_coord <= interval.right) {
add_coverage(node_idx); add_coverage(node_idx);
} else { } else {
if(interval.left < left_child(node_idx).right_coord) { if(interval.left < left_child(node_idx).right_coord) {
add_interval(interval, left_child_idx(node_idx)); visit_to.push(left_child_idx(node_idx));
} }
if(right_child(node_idx).left_coord < interval.right) { if(right_child(node_idx).left_coord < interval.right) {
add_interval(interval, right_child_idx(node_idx)); visit_to.push(right_child_idx(node_idx));
} }
update_covered_length(node_idx); if(!_nodes[node_idx].covered()) {
update_to.push_back(node_idx);
}
}
}
for(auto update_idx : update_to) {
update_covered_length(update_idx);
} }
} }
void SegmentTree::remove_interval(Interval interval, Index node_idx) { void SegmentTree::remove_interval(Interval interval) {
std::stack<Index> visit_to;
std::vector<Index> update_to;
visit_to.push(0);
while(!visit_to.empty()) {
Index node_idx = visit_to.top();
visit_to.pop();
if (interval.left <= _nodes[node_idx].left_coord && _nodes[node_idx].right_coord <= interval.right) { if (interval.left <= _nodes[node_idx].left_coord && _nodes[node_idx].right_coord <= interval.right) {
remove_coverage(node_idx); remove_coverage(node_idx);
} else { } else {
if(interval.left < left_child(node_idx).right_coord) { if(interval.left < left_child(node_idx).right_coord) {
remove_interval(interval, left_child_idx(node_idx)); visit_to.push(left_child_idx(node_idx));
} }
if(right_child(node_idx).left_coord < interval.right) { if(right_child(node_idx).left_coord < interval.right) {
remove_interval(interval, right_child_idx(node_idx)); visit_to.push(right_child_idx(node_idx));
} }
update_covered_length(node_idx); if(!_nodes[node_idx].covered()) {
update_to.push_back(node_idx);
}
}
}
for(auto update_idx : update_to) {
update_covered_length(update_idx);
} }
} }

25
segment_tree.h
View file

@ -15,6 +15,7 @@ struct TreeNode {
Coordinate right_coord; Coordinate right_coord;
Unit covered_length; Unit covered_length;
inline Unit segment_length(); inline Unit segment_length();
inline bool covered();
}; };
@ -30,8 +31,8 @@ public:
SegmentTree(const std::vector<RectCoord>& coords); SegmentTree(const std::vector<RectCoord>& coords);
inline Unit length_covered_intervals(); inline Unit length_covered_intervals();
inline void add_interval(Interval interval); void add_interval(Interval interval);
inline void remove_interval(Interval interval); void remove_interval(Interval interval);
private: private:
inline static Index left_child_idx(Index node_idx); inline static Index left_child_idx(Index node_idx);
@ -41,8 +42,6 @@ private:
inline void add_coverage(Index node_idx); inline void add_coverage(Index node_idx);
inline void remove_coverage(Index node_idx); inline void remove_coverage(Index node_idx);
inline void update_covered_length(Index node_idx); inline void update_covered_length(Index node_idx);
void add_interval(Interval interval, Index node_idx);
void remove_interval(Interval interval, Index node_idx);
inline bool is_leaf(Index node_idx); inline bool is_leaf(Index node_idx);
}; };
@ -65,17 +64,9 @@ Unit SegmentTree::length_covered_intervals() {
return _nodes.front().covered_length; return _nodes.front().covered_length;
} }
void SegmentTree::add_interval(Interval interval) {
add_interval(interval, 0);
}
void SegmentTree::remove_interval(Interval interval) {
remove_interval(interval, 0);
}
void SegmentTree::add_coverage(Index node_idx) { void SegmentTree::add_coverage(Index node_idx) {
++(_nodes[node_idx].coverage); ++(_nodes[node_idx].coverage);
update_covered_length(node_idx); _nodes[node_idx].covered_length = _nodes[node_idx].segment_length();
} }
void SegmentTree::remove_coverage(Index node_idx) { void SegmentTree::remove_coverage(Index node_idx) {
@ -92,9 +83,7 @@ Index SegmentTree::right_child_idx(Index node_idx) {
} }
void SegmentTree::update_covered_length(Index node_idx) { void SegmentTree::update_covered_length(Index node_idx) {
if (_nodes[node_idx].coverage > 0) { if (is_leaf(node_idx)) {
_nodes[node_idx].covered_length = _nodes[node_idx].segment_length();
} else if (is_leaf(node_idx)) {
_nodes[node_idx].covered_length = 0; _nodes[node_idx].covered_length = 0;
} else { } else {
_nodes[node_idx].covered_length = \ _nodes[node_idx].covered_length = \
@ -106,6 +95,10 @@ Unit TreeNode::segment_length() {
return right_coord - left_coord; return right_coord - left_coord;
} }
bool TreeNode::covered() {
return coverage > 0;
}
bool SegmentTree::is_leaf(Index node_idx) { bool SegmentTree::is_leaf(Index node_idx) {
return node_idx > _num_meta_nodes; return node_idx > _num_meta_nodes;
} }