solved: 82

Author: ryoppippi

code/82.remove-duplicates-from-sorted-list-ii.ts

@@ -0,0 +1,43 @@
+class ListNode {
+  val: number
+  next: ListNode | null
+  constructor(val?: number, next?: ListNode | null) {
+    this.val = (val===undefined ? 0 : val)
+    this.next = (next===undefined ? null : next)
+  }
+}
+
+// @leet start
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+
+function deleteDuplicates(head: ListNode | null): ListNode | null {
+  const nm = new Map<number, number>( )
+  while (head) {
+    nm.set(head.val, (nm.get(head.val) ?? 0) + 1)
+    head = head.next
+  }
+
+  /** get numbers which appears only once */
+  const arr = Array.from(nm.entries()).filter(([_, v]) => v === 1).map(([k, _]) => k).sort((a, b) => a - b)
+
+  /** create a new list */
+  const dummy = new ListNode()
+  let current = dummy
+  arr.forEach((v) => {
+    current.next = new ListNode(v)
+    current = current.next
+  })
+
+  return dummy.next
+};
+// @leet end