Added basic DSU implementation

Author: RealA10N

dsu.go

@@ -0,0 +1,46 @@
+package dsu
+
+const noParent = ^uint(0)
+
+type Dsu struct {
+	parent []uint
+	size   []uint
+}
+
+// Create a new Disjoint Set Union data structure with n elements.
+// The elements are referred to by their index in the range [0, n).
+// The element values are not stored explicitly in the data structure,
+// and the user of the data structure is responsible for maintaining
+// a correspondence between the element values and their indices.
+func NewDsu(n uint) *Dsu {
+	dsu := &Dsu{
+		parent: make([]uint, n),
+		size:   make([]uint, n),
+	}
+	for i := range dsu.parent {
+		dsu.parent[i] = noParent
+		dsu.size[i] = 1
+	}
+	return dsu
+}
+
+func (d *Dsu) Find(v uint) uint {
+	if d.parent[v] == noParent {
+		return v
+	}
+	d.parent[v] = d.Find(d.parent[v])
+	return d.parent[v]
+}
+
+func (d *Dsu) Union(v1, v2 uint) {
+	v1 = d.Find(v1)
+	v2 = d.Find(v2)
+	if v1 == v2 {
+		return
+	}
+	if d.size[v1] < d.size[v2] {
+		v1, v2 = v2, v1
+	}
+	d.parent[v2] = v1
+	d.size[v1] += d.size[v2]
+}