Union Find木のD言語の実装

unionfind.d

class UnionFind(T) {
	T[] arr;
	this(ulong n) {
		arr.length = n+1;
		arr[] = -1;
	}
	T root(T x) {
		return arr[x] < 0 ? x : root(arr[x]);
	}
	bool same(T x, T y) {
		return root(x) == root(y);
	}
	bool unite(T x, T y) {
		x = root(x);
		y = root(y);
		if(x == y) return false;
		if(arr[x] > arr[y]) swap(x, y);
		arr[x] += arr[y];
		arr[y] = x;
		return true;
	}
	T size(T a) {
		return -arr[root(a)];
	}
}