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Golang Implementations/Package Dependencies/unionds/unionfind.go

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+/*
+************Union-Find/ Disjoint-Set Data Structure************
+Based on explanation from Page No. 98 to 103 and also from https://bit.ly/337fmv1 
+particularly used path compression technique while implementing
+Direct URL for above Shortened URL: https://opendsa-server.cs.vt.edu/ODSA/Books/Everything/html/UnionFind.html
+For Complexities of these operations, refer to Pg. No. 96
+***************************************************************
+
+Usage:
+	import this "unionds" package in Go main file
+
+Initialize Union-Find Data Structure:
+Syntax: Initialize(vertices ...string) Partition {...}
+	Ex: uds := Initialize("1", "2", "3", "4", "5", "6") 
+	Output: Partition{P: []Node{[{1 0 1} {2 1 1} {3 2 1} {4 3 1} {5 4 1} {6 5 1}]} 
+					  Index: map[1:0 2:1 3:2 4:3 5:4 6:5]}
+Finding to which set in the partition the given key belongs to:
+Given a key, it returns the parent of the set this key belongs to
+Syntax: uds.Find(key string) int {...}
+	Ex: uds.Find("5") -> key "5" belongs to a set whose parent is 4, so it returns 4
+Combine two sets by giving any of the keys in those sets using Union() method
+Given two keys, it searches for the sets to which these two keys belongs to and merge these two sets
+Syntax: uds.UnionUnion(key1, key2 string)
+	Ex: 
+	Step 1: uds := Initialize("1", "2", "3", "4", "5", "6")
+	Output: Partition{P: []Node{[{1 0 1} {2 1 1} {3 2 1} {4 3 1} {5 4 1} {6 5 1}]} 
+					  Index: map[1:0 2:1 3:2 4:3 5:4 6:5]}
+	Step 2:	uds.Union("5", "6")
+	Output: Partition{P: []Node{[{1 0 1} {2 1 1} {3 2 1} {4 3 1} {5 4 1} {6 4 1}]} 
+					  Index: map[1:0 2:1 3:2 4:3 5:4 6:5]}
+	The sets of those two keys "5", "6" are merged. Now key "6" parent is "5" thus they both are 
+	linked together as a single set
+*/
+
+
+
+
+package unionds
+
+import (
+	"fmt"
+)
+
+
+type Node struct {
+	N string // Name of the node N
+	P int // Parent's Index P
+	S int // Size S
+}
+
+type Partition struct {
+	P []Node // Parition P
+	Index map[string]int // Map for index of each node's name N
+}
+
+func Initialize(vertices ...string) Partition {
+	slice := Partition{P:[]Node{}, Index:map[string]int{}}
+	for _, vertex := range vertices {
+		slice.P = append(slice.P, Node{vertex, len(slice.P), 1})
+		slice.Index[vertex] = len(slice.P)-1
+	}
+	return slice
+}
+
+
+func (p *Partition) Find(key string) int {
+	idx := p.Index[key]
+	for p.P[idx].P != idx {
+		idx = p.P[idx].P
+	}
+	return p.P[idx].P 
+}
+
+func (p *Partition) Union(key1, key2 string) {
+	root1Idx := p.Find(key1)
+	root2Idx := p.Find(key2)
+	if root1Idx != root2Idx {
+		if p.P[root1Idx].S >= p.P[root2Idx].S {
+			p.P[root2Idx].P = root1Idx
+			p.P[root1Idx].S += p.P[root2Idx].S
+		} else {
+			p.P[root1Idx].P = root2Idx
+			p.P[root2Idx].S += p.P[root1Idx].S
+		}
+	}
+}
+
+
+func (p *Partition) Show() {
+	fmt.Println(p.P)
+}