new file: sets/unionFind.go

README.md

@@ -15,10 +15,11 @@
 - [x] Heap (min/max)
 - [ ] Trie
 
-## Hash Based — key/value
+## Sets
 
-- [ ] Hash Map
-- [ ] Hash Set
+- [ ] Union Find
+- [ ] Bloom filter
+- [ ] HyperLogLog
 
 # Algorithms ωψγ
 

sets/unionFind.go

@@ -0,0 +1,81 @@
+package sets
+
+type UnionFind struct {
+	disjointed int
+	parent     []int
+	rank       []int
+}
+
+// NewUnionFind() -> Creates an disjoint set
+func NewUnionFind(uniqueElements int) *UnionFind {
+	// counts from 0 correction
+	uniqueElements += 1
+
+	uf := &UnionFind{
+		parent:     make([]int, uniqueElements),
+		rank:       make([]int, uniqueElements),
+		disjointed: uniqueElements - 1,
+	}
+
+	for i := range uf.parent {
+		uf.parent[i] = i
+	}
+
+	return uf
+}
+
+// Find() -> returns the root of a node
+func (uf *UnionFind) Find(val int) int {
+	root := val
+
+	// find root of val
+	for uf.parent[root] != root {
+		root = uf.parent[root]
+	}
+
+	// point every node on the path directly at root
+	current := val
+	for uf.parent[current] != root {
+		current, uf.parent[current] = uf.parent[current], root
+	}
+
+	return root
+}
+
+// Union() -> creates an Union of 2 values, returns true if success
+func (uf *UnionFind) Union(a int, b int) bool {
+	node1 := uf.Find(a)
+	node2 := uf.Find(b)
+
+	if node1 == node2 {
+		return false
+	}
+
+	winner, loser := node1, node2
+	if uf.rank[winner] < uf.rank[loser] {
+		winner, loser = loser, winner
+	}
+
+	// merge
+	uf.parent[loser] = winner
+
+	if uf.rank[winner] == uf.rank[loser] {
+		uf.rank[winner]++
+	}
+	uf.disjointed--
+
+	return true
+}
+
+// IsUnion() -> returns true if the parameters have the same root
+func (uf UnionFind) IsUnion(a int, b int) bool {
+	if uf.Find(a) == uf.Find(b) {
+		return true
+	}
+	return false
+}
+
+// Disjointed() -> returns the count of disjointed sets remaining
+func (uf UnionFind) Disjointed() int {
+	return uf.disjointed
+}