Merge pull request loiane#181 from anthonycampbell/gale_shapley

Adding gale-shapley algorithm

Author: loiane

src/js/algorithms/graph/gale-shapley.js

@@ -0,0 +1,77 @@
+class Person {
+	constructor(id, gender, ranks, rankIndex, status = "single") {
+		this.id = id
+		this.gender = gender
+		this.ranks = ranks
+		this.i = rankIndex
+		this.status = status
+		this.partner = null
+	}
+}
+
+function galeShapley(proposers, reviewers) {
+	let perfectMatching = new Map()
+	for (let [pid, p] of proposers) {
+		while (p.i < p.ranks.length) {
+			let rid = p.ranks[p.i]
+			let r = reviewers.get(rid)
+			p.i++
+			if (r.status === "single") {
+				r.status = "engaged"
+				r.partner = p
+				p.partner = r
+				perfectMatching.set(pid, rid)
+				proposers.delete(pid)
+				break
+			} else if (r.status === "engaged" && r.ranks.get(pid) < r.ranks.get(r.partner.id)) {
+				perfectMatching.delete(r.partner.id)
+				proposers.set(r.partner.id, r.partner)
+				proposers.delete(pid)
+				r.partner.partner = null
+				r.partner = p
+				p.partner = r
+				perfectMatching.set(pid, rid)
+				break
+			}
+		}
+	}
+	return perfectMatching
+}
+
+let men = new Map()
+let women = new Map()
+//O(n^2)
+function createPeople(n, gender, set) {
+	for (let i = 0; i < n; i++) {
+		let id = i
+		let rankIndex = 0
+		let g = gender
+		let ranks = new Array(n)
+		let p
+		for (let i = 0; i < n; i++) ranks[i] = i
+		shuffle(ranks)
+		if (gender == 'w') {
+			let wRanks = new Map()
+			for (let i = 0; i < n; i++) wRanks.set(i, ranks[i])
+			p = new Person(id, g, wRanks, null)
+		} else {
+			p = new Person(id, g, ranks, rankIndex)
+		}
+		set.set(i, p)
+	}
+}
+
+//fisher-yates shuffle O(n)
+function shuffle(array) {
+	for (let i = array.length - 1; i >= 0; i--) {
+		let j = Math.floor(Math.random() * (i + 1))
+		let temp = array[i]
+		array[i] = array[j]
+		array[j] = temp
+	}
+}
+
+createPeople(4, 'm', men)
+createPeople(4, 'w', women)
+let stableMatching = galeShapley(men, women)
+console.log(stableMatching)