Add util::dsu

libs/util/include/psemek/util/dsu.hpp

@@ -0,0 +1,54 @@
+#pragma once
+
+#include <vector>
+#include <cstdint>
+
+namespace psemek::util
+{
+
+	template <typename Index = std::uint32_t>
+	struct dsu
+	{
+		dsu() = default;
+		dsu(Index count);
+
+		void combine(Index x, Index y);
+		Index find(Index x);
+
+	private:
+		std::vector<Index> parent_;
+		std::vector<Index> size_;
+	};
+
+	template <typename Index>
+	dsu<Index>::dsu(Index count)
+		: parent_(count)
+		, size_(count, 1)
+	{
+		for (Index i = 0; i < count; ++i)
+			parent_[i] = i;
+	}
+
+	template <typename Index>
+	void dsu<Index>::combine(Index x, Index y)
+	{
+		x = find(x);
+		y = find(y);
+		if (x != y)
+		{
+			if (size_[x] < size_[y])
+				std::swap(x, y);
+			parent_[y] = x;
+			size_[x] += size_[y];
+		}
+	}
+
+	template <typename Index>
+	Index dsu<Index>::find(Index x)
+	{
+		if (parent_[x] == x)
+			return x;
+		return parent_[x] = find(parent_[x]);
+	}
+
+}