❌ [143] a1

Author: enkr1

143/my_solution.js

@@ -0,0 +1,117 @@
+// Reorder List
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+class ListNode {
+  constructor(val, next) {
+    this.val = (val === undefined ? 0 : val);
+    this.next = (next === undefined ? null : next);
+  }
+}
+
+/**
+ * @param {ListNode} head
+ * @return {void} Do not return anything, modify head in-place instead.
+ */
+const reorderList = (head) => {
+  // let slow = head, fast = head.next;//, reversed = new ListNode(), dummy = new ListNode(), result = dummy;
+  // while (fast && fast.next) {
+  //   slow = slow.next
+  //   fast = fast.next.next;
+  // }
+  //
+  // console.log("slow")
+  // console.log(slow)
+  // console.log("fast")
+  // console.log(fast)
+
+  let slow = head, fast = head, counter = head, reversed = new ListNode(), dummy = new ListNode(), result = dummy;
+
+  // console.log("fast")
+  // console.log(fast)
+
+  // let count = 0;
+  // while (counter.next) {
+  //   count++;
+  //   counter = counter.next;
+  // }
+
+  // while (count > 0) {
+  //   reversed.next = new ListNode(fast.val, reversed.next);
+  //   fast = fast.next;
+  // }
+
+  console.log("slow")
+  console.log(slow)
+  reversed = reversed.next;
+  console.log("reversed")
+  console.log(reversed)
+  console.log("count: " + count)
+
+  while (slow || reversed) {
+    // console.log(`-> slow:${slow.val} & reversed:${reversed.val}`)
+    // when reversed is null (on case of 3 linked list only), or  same values.
+    if ((null === reversed) || (reversed && (slow.val === reversed.val))) {
+      // if (slow.val === reversed.val) {
+      console.log('------------------> FOUnd same')
+      console.log(dummy)
+      slow.next = null;
+      dummy.next = slow;
+      slow = null;
+      reversed = null;
+    } else {
+      // dummy.next = new ListNode(slow.val, reversed);
+      dummy.next = slow;
+      slow = slow.next;
+      dummy = dummy.next;
+
+      dummy.next = reversed;
+      reversed = reversed.next;
+      dummy = dummy.next;
+
+      console.log("---> dummy")
+      console.log(dummy)
+    }
+
+  }
+  result = result.next
+  console.log("result")
+  console.log(result)
+  while (result) {
+    console.log("check")
+    console.log(result.val)
+    result = result.next;
+  }
+};
+
+
+
+// reorderList(
+//   new ListNode(1,
+//     new ListNode(2,
+//       new ListNode(3,
+//         new ListNode(4))
+//     )
+//   )
+// )
+
+// reorderList(
+//   new ListNode(1,
+//     new ListNode(2,
+//       new ListNode(3)
+//     )
+//   )
+// )
+
+
+reorderList(
+  new ListNode(1,
+    new ListNode(2,
+      new ListNode(3,
+        new ListNode(4,
+          new ListNode(5))))))

143/solution.js

@@ -0,0 +1,49 @@
+// Reorder List
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+class ListNode {
+  constructor(val, next) {
+    this.val = (val === undefined ? 0 : val);
+    this.next = (next === undefined ? null : next);
+  }
+}
+
+/**
+ * @param {ListNode} head
+ * @return {void} Do not return anything, modify head in-place instead.
+ */
+const reorderList = (head) => {
+  if (null === head.next) return head;
+  let slow = head, fast = head.next.next, reversed = new ListNode(), dummy = new ListNode(), result = dummy;
+
+  while (fast) {
+    reversed.next = new ListNode(fast.val, reversed.next);
+    fast = fast.next;
+  }
+
+  reversed = reversed.next;
+
+  while (slow && reversed) {
+    if (slow.val === reversed.val) {
+      dummy.next = reversed;
+      slow = null;
+      reversed = null;
+    } else {
+      dummy.next = slow;
+      slow = slow.next;
+      dummy = dummy.next;
+
+      dummy.next = reversed;
+      reversed = reversed.next;
+      dummy = dummy.next;
+    }
+
+  }
+  head = result.next;
+};