test case
i dont understand i have problems with one test case on input i have and it fails
1. list1 = [];
2. list2 = [0];
Please take a look at my solution and give me help with that.
struct ListNode* mergeTwoLists(struct ListNode* list1, struct ListNode* list2) {
struct ListNode* result = NULL;
struct ListNode* temp1 = list1;
struct ListNode* temp2 = list2;
while(temp1 != NULL && temp2 != NULL){
if(temp1 != NULL && temp2 == NULL){
append(&result, temp1->val);
temp1 = temp1->next;
}
if(temp1 == NULL && temp2 != NULL){
append(&result, temp2->val);
temp2 = temp2->next;
}
if(temp1->val < temp2->val){
append(&result, temp1->val);
temp1 = temp1->next;
}
else{
append(&result, temp2->val);
temp2 = temp2->next;
}
if(temp1->val == temp2->val){
append(&result, temp1->val);
append(&result, temp2->val);
temp1 = temp1->next;
temp2 = temp2->next;
}
}
return result;
}
Answer
The top of your loop is:
while(temp1 != NULL && temp2 != NULL){
if(temp1 != NULL && temp2 == NULL){
How many times is temp2 == NULL inside that loop?
You need to move the first two conditions out of the loop you have. You need two loops after the current loop:
while (temp1 != NULL) { append(&result, temp1->val); temp1 = temp1->next; }
while (temp2 != NULL) { append(&result, temp2->val); temp2 = temp2->next; }
At most one of those loops will actually run.
You also have problems in the rest of the body of your loop. You should only execute one of three actions. Thus:
struct ListNode *mergeTwoLists(struct ListNode *list1, struct ListNode *list2)
{
struct ListNode *result = NULL;
struct ListNode *temp1 = list1;
struct ListNode *temp2 = list2;
while (temp1 != NULL && temp2 != NULL)
{
if (temp1->val < temp2->val)
{
append(&result, temp1->val);
temp1 = temp1->next;
}
else if (temp1->val > temp2->val)
{
append(&result, temp2->val);
temp2 = temp2->next;
}
else
{
assert(temp1->val == temp2->val);
append(&result, temp1->val);
append(&result, temp2->val);
temp1 = temp1->next;
temp2 = temp2->next;
}
}
while (temp1 != NULL)
{
append(&result, temp1->val);
temp1 = temp1->next;
}
while (temp2 != NULL)
{
append(&result, temp2->val);
temp2 = temp2->next;
}
return result;
}