vivekanand44 / codes-youtube-videos Goto Github PK

Hi, I saw your video on the merge of two sorted list. The algorithm will not work in one edge case
Since at the beginning you are setting s, p and q the algorithm assumes that in the lists there are at least 2 nodes. It will not work if one of the lists contain 1 node only as the p pointer will be set to null and so it will print that single node only. The second list will be lost

Please double check and rectify
When you initialise you need to check if one of the lists have a single node. In that case you would need to create the link from that single node to the other list and the algorithm will terminate immediately without the nedd to continue

For this I believe you need to add this check
if(p.next === q || q.next === p) return newHead
after you have properly initialised the p, q and s based on this edge case

if(p && q){
    if(p.val <= q.val ) {
        s = p
        **if(p.next) {
                p = p.next
        }
        else {
            p.next = q
        }**
    } else {
        s = q
        **if(q.next) {
                q = q.next
            } else {
                q.next = p
    }**
}

in bold the missing checks
Thanks