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Telegram/SourceFiles/statistics/segment_tree.h

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+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+#include "statistics/statistics_types.h"
+
+namespace Statistic {
+
+class SegmentTree final {
+public:
+	SegmentTree() = default;
+	SegmentTree(std::vector<ChartValue> array);
+
+	[[nodiscard]] bool empty() const {
+		return _array.empty();
+	}
+	[[nodiscard]] explicit operator bool() const {
+		return !empty();
+	}
+
+	[[nodiscard]] ChartValue rMaxQ(int from, int to);
+	[[nodiscard]] ChartValue rMinQ(int from, int to);
+
+private:
+	struct Node final {
+		ChartValue sum = 0;
+		ChartValue max = 0;
+		ChartValue min = 0;
+
+		struct PendingVal {
+			[[nodiscard]] explicit operator bool() const {
+				return available;
+			}
+			ChartValue value = 0;
+			bool available = false;
+		};
+		PendingVal pendingVal;
+
+		int from = 0;
+		int to = 0;
+
+		[[nodiscard]] int size() {
+			return to - from + 1;
+		}
+	};
+
+	void build(ChartValue v, int from, int size);
+	void propagate(ChartValue v);
+	void change(Node &n, ChartValue value);
+
+	[[nodiscard]] ChartValue rMaxQ(ChartValue v, int from, int to);
+	[[nodiscard]] ChartValue rMinQ(ChartValue v, int from, int to);
+
+	[[nodiscard]] bool contains(int from1, int to1, int from2, int to2) const;
+	[[nodiscard]] bool intersects(
+		int from1,
+		int to1,
+		int from2,
+		int to2) const;
+
+	std::vector<ChartValue> _array;
+	std::vector<Node> _heap;
+
+};
+
+} // namespace Statistic