Create 0721-accounts-merge.kt

Author: a93a

kotlin/0721-accounts-merge.kt

@@ -0,0 +1,62 @@
+class DSU(val n: Int) {
+
+    val parent = IntArray(n) {it}
+    val rank = IntArray(n) {1}
+
+    fun find(x: Int): Int {
+        if (x != parent[x])
+            parent[x] = find(parent[x])
+        return parent[x]
+    }
+
+    fun union(x: Int, y: Int): Boolean {
+        val pX = find(x)
+        val pY = find(y)
+
+        if(pX == pY)
+            return false
+        
+        if (rank[pX] > rank[pY]) {
+            parent[pY] = pX
+            rank[pX] += rank[pY]
+        } else {
+            parent[pX] = pY
+            rank[pY] += rank[pX]
+        }
+
+        return true
+    }
+}
+
+class Solution {
+    fun accountsMerge(accounts: List<List<String>>): List<List<String>> {
+        val uf = DSU(accounts.size)
+        val emailToAcc = HashMap<String, Int>()
+
+        for ((i,accs) in accounts.withIndex()) {
+            for (j in 1..accs.lastIndex) {
+                val e = accs[j]
+                if (e in emailToAcc.keys) {
+                    uf.union(i, emailToAcc[e]!!)
+                } else {
+                    emailToAcc[e] = i
+                }
+            }
+        }
+
+        val emails = hashMapOf<Int, ArrayList<String>>()
+        for ((e, i) in emailToAcc) {
+            val main = uf.find(i)
+            emails[main] = emails.getOrDefault(main, ArrayList<String>()).apply { this.add(e) }
+        }
+
+        val res = ArrayList<ArrayList<String>>()
+        for ((i, em) in emails.entries) {
+            em.sort()
+            em.add(0, accounts[i][0])
+            res.add(em)
+        }
+
+        return res
+    }
+}