Create solution_9.js

01. DataStructures/01. Linked List/1. Singly-Linked-List/InterviewBit Questions/09. Add two no. as List/solution_9.js

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+// REMEMBER 
+// you need legit linked list for input to test this solution, which you don't have but you have checked it on leet code
+// it's workin fine. just push it on github as it is. it's legit solution and it's working.
+
+
+var addTwoNumbers = function(l1, l2) {
+ if(!l1 || !l2) return null;
+
+ const l1Length = getLen(l1);
+ const l2Length = getLen(l2);
+ const firstNodeRef = l1;
+ let carry = 0;
+
+ // appending zeors 
+ if(l1Length !== l2Length) {
+ if(l2Length < l1Length) {
+ l2 = appendZeros(l2, l1Length - l2Length);
+ } else {
+ l1 = appendZeros(l1, l2Length - l1Length);
+ }
+ }
+
+ // ref to one node before the current node.
+ let prev;
+ while(l1) {
+ const total = l1.val + l2.val + carry;
+ l1.val = (total) % 10;
+ if(total > 9) {
+ carry = 1;
+ } else {
+ carry = 0;
+ }
+ prev = l1;
+ l1 = l1.next;
+ l2 = l2.next;
+ }
+ // cheking if there is a carry at the last digit node.
+ if(carry == 1) {
+ prev.next = new ListNode(1);
+ }
+ return firstNodeRef;
+};
+
+// get the length of linklist.
+function getLen(node) {
+ let count = 0;
+ while(node) {
+ count++;
+ node = node.next;
+ }
+ return count;
+}
+// append zeros at the end of shorter linklist.
+function appendZeros(node, diff) {
+ const temp = node;
+ while(node.next) {
+ node = node.next;
+ }
+ let count = 0;
+ while(count < diff) {
+ node.next = new ListNode(0);
+ node = node.next;
+ count++;
+ }
+ node = temp; 
+
+ return node;
+}