@@ -0,0 +1,56 @@
+var smallestEquivalentString = function(A, B, S) {
+const set = new DisjointSet()
+
+for (let i = 0; i < A.length; i++) {
+const aPos = posForChar(A[i])
+const bPos = posForChar(B[i])
+set.union(aPos, bPos)
+}
+
+const result = []
+for (const char of S) {
+const sPos = posForChar(char)
+const parent = set.find(sPos)
+result.push(charForPos(parent))
+}
+
+return result.join('')
+};
+
+class DisjointSet {
+constructor() {
+this.parent = []
+for (let i = 0; i < 26; i++)
+this.parent[i] = i
+}
+
+find(p) {
+let root = p
+while (root !== this.parent[root])
+root = this.parent[root]
+
+while (p !== root) {
+const next = this.parent[p]
+this.parent[p] = root
+p = next
+}
+
+return root
+}
+
+union(p, q) {
+const rootP = this.find(p)
+const rootQ = this.find(q)
+
+if (rootP === rootQ) return
+
+if (rootP > rootQ) {
+this.parent[rootP] = rootQ
+} else {
+this.parent[rootQ] = rootP
+}
+}
+}
+
+const posForChar = char => char.charCodeAt(0) - 'a'.charCodeAt(0)
+const charForPos = pos => String.fromCharCode(pos + 'a'.charCodeAt(0))