From 61f468c15029c68aaa35a384b1cec17a56976638 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maximilian=20Ke=C3=9Fler?= <git@maximilian-kessler.de>
Date: Sun, 17 Apr 2022 13:57:09 +0200
Subject: [PATCH] check integrity of tree. fix bug regarding updating

---
 segment_tree.cpp | 39 ++++++++++++++++++++++++++++++---------
 segment_tree.h   |  1 +
 2 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/segment_tree.cpp b/segment_tree.cpp
index 6fcd570..a985d2c 100644
--- a/segment_tree.cpp
+++ b/segment_tree.cpp
@@ -35,8 +35,9 @@ SegmentTree::SegmentTree(const std::vector<RectCoord> &coords):
 }
 
 void SegmentTree::add_interval(Interval interval) {
+    check_integrity();
     std::stack<Index> visit_to;
-    std::vector<Index> update_to;
+    std::stack<Index> update_to;
     visit_to.push(0);
     while(!visit_to.empty()) {
         Index node_idx = visit_to.top();
@@ -51,18 +52,21 @@ void SegmentTree::add_interval(Interval interval) {
                 visit_to.push(right_child_idx(node_idx));
             }
             if(!_nodes[node_idx].covered()) {
-                update_to.push_back(node_idx);
+                update_to.push(node_idx);
             }
         }
     }
-    for(auto update_idx : update_to) {
-        update_covered_length(update_idx);
+    while(!update_to.empty()) {
+        update_covered_length(update_to.top());
+        update_to.pop();
     }
+    check_integrity();
 }
 
 void SegmentTree::remove_interval(Interval interval) {
+    check_integrity();
     std::stack<Index> visit_to;
-    std::vector<Index> update_to;
+    std::stack<Index> update_to;
     visit_to.push(0);
     while(!visit_to.empty()) {
         Index node_idx = visit_to.top();
@@ -77,11 +81,28 @@ void SegmentTree::remove_interval(Interval interval) {
                 visit_to.push(right_child_idx(node_idx));
             }
             if(!_nodes[node_idx].covered()) {
-                update_to.push_back(node_idx);
+                update_to.push(node_idx);
             }
         }
     }
-    for(auto update_idx : update_to) {
-        update_covered_length(update_idx);
+    while(!update_to.empty()) {
+        update_covered_length(update_to.top());
+        update_to.pop();
     }
-}
\ No newline at end of file
+    check_integrity();
+}
+
+void SegmentTree::check_integrity() {
+    for(Index node_idx = 0 ; node_idx < _nodes.size(); ++node_idx) {
+        if(_nodes[node_idx].covered()) {
+            assert(_nodes[node_idx].covered_length == _nodes[node_idx].segment_length());
+        } else {
+            if(is_leaf(node_idx)) {
+                assert(_nodes[node_idx].covered_length == 0);
+            } else {
+                assert(_nodes[node_idx].covered_length == \
+                left_child(node_idx).covered_length + right_child(node_idx).covered_length);
+            }
+        }
+    }
+}
diff --git a/segment_tree.h b/segment_tree.h
index d070556..2ee53d3 100644
--- a/segment_tree.h
+++ b/segment_tree.h
@@ -33,6 +33,7 @@ public:
     inline Unit length_covered_intervals();
     void add_interval(Interval interval);
     void remove_interval(Interval interval);
+    void check_integrity();
 
 private:
     inline static Index left_child_idx(Index node_idx);