solved: 206

Author: ryoppippi

code/206.reverse-linked-list.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 reverseList(head: ListNode | null): ListNode | null {
+  const n: number[] = [];
+  while (head) {
+    n.push(head.val);
+    head = head.next;
+  }
+
+  /** reverse list */
+  const nR = n.reverse();
+
+  /** create the start node ( empty node, so the actual node stats from next) */
+  let node = new ListNode();
+  const headNode = node;
+  for (const i of nR) {
+    node.next = new ListNode(i);
+    node = node.next;
+  }
+
+  return headNode.next;
+}
+// @leet end
+