Added: TypeScript solutions 2,206,21

typescript/2-Add-Two-Numbers.ts

@@ -0,0 +1,37 @@
+/**
+ * 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 addTwoNumbers(
+ l1: ListNode | null,
+ l2: ListNode | null
+): ListNode | null {
+ let dummyNode: ListNode = new ListNode()
+ let currentNode: ListNode = dummyNode
+ let carry: number = 0
+
+ while (l1 !== null || l2 !== null || carry !== 0) {
+ const val1 = l1 !== null ? l1.val : 0
+ const val2 = l2 !== null ? l2.val : 0
+
+ const sum: number = val1 + val2 + carry
+ const value: number = sum % 10
+ const newLinkedList: ListNode = new ListNode(value)
+ currentNode.next = newLinkedList
+ currentNode = newLinkedList
+ carry = Math.floor(sum / 10)
+
+ l1 = l1 !== null ? l1.next : null
+ l2 = l2 !== null ? l2.next : null
+ }
+
+ return dummyNode.next
+}

typescript/206-Reverse-Linked-List.ts

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+/**
+ * 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 {
+ let prev: ListNode | null = null
+
+ while (head) {
+ let ele = head.next
+ head.next = prev
+ prev = head
+ head = ele
+ }
+ return prev
+}

typescript/21-Merge-Two-Sorted-Lists.ts

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+/**
+ * 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 mergeTwoLists(
+ list1: ListNode | null,
+ list2: ListNode | null
+): ListNode | null {
+ let dummyList: ListNode = new ListNode(0)
+ let currentNode: ListNode = dummyList
+
+ while (list1 !== null && list2 !== null) {
+ if (list1.val < list2.val) {
+ currentNode.next = list1
+ list1 = list1.next
+ } else {
+ currentNode.next = list2
+ list2 = list2.next
+ }
+
+ currentNode = currentNode.next
+ }
+
+ if (list1 !== null) currentNode.next = list1
+ if (list2 !== null) currentNode.next = list2
+
+ return dummyList.next
+}