输入两个递增排序的链表,合并这两个链表并使新链表中的结点仍然是按照递增排序的。
struct ListNode
{
int m_nValue;
ListNode* m_pNext;
};
ListNode* Merge(ListNode* pHead1,ListNode* pHead2)
{
if(pHead1 == NULL)
return pHead2;
else if(pHead2 == NULL)
return pHead1;
ListNode *pMergeHead = NULL;
if(pHead1->m_nValue < pHead2->m_nValue)
{
pMergeHead = pHead1;
pMergeHead->m_pNext = Merge(pHead1->m_pNext,pHead2);
}
else
{
pMergeHead = pHead2;
pMergeHead->m_pNext = Merge(pHead1,pHead2->m_pNext);
}
return pMergeHead;
}
ListNode* CreateListNode(int value)
{
ListNode* pNode = new ListNode();
pNode->m_nValue = value;
pNode->m_pNext = NULL;
return pNode;
}
void ConnectListNodes(ListNode* pCurrent, ListNode* pNext)
{
if(pCurrent == NULL)
{
printf("Error to connect two nodes.\n");
}
pCurrent->m_pNext = pNext;
}
void PrintListNode(ListNode* pNode)
{
if(pNode == NULL)
{
printf("The node is NULL\n");
}
else
{
printf("The key in node is %d.\n", pNode->m_nValue);
}
}
void PrintList(ListNode* pHead)
{
printf("PrintList starts.\n");
ListNode* pNode = pHead;
while(pNode != NULL)
{
printf("%d\t", pNode->m_nValue);
pNode = pNode->m_pNext;
}
printf("\nPrintList ends.\n");
}
void DestroyList(ListNode* pHead)
{
ListNode* pNode = pHead;
while(pNode != NULL)
{
pHead = pHead->m_pNext;
delete pNode;
pNode = pHead;
}
}
ListNode* Test(char* testName, ListNode* pHead1, ListNode* pHead2)
{
if(testName != NULL)
printf("%s begins:\n", testName);
printf("The first list is:\n");
PrintList(pHead1);
printf("The second list is:\n");
PrintList(pHead2);
printf("The merged list is:\n");
ListNode* pMergedHead = Merge(pHead1, pHead2);
PrintList(pMergedHead);
printf("\n\n");
return pMergedHead;
}
void Test1()
{
ListNode* pNode1 = CreateListNode(1);
ListNode* pNode3 = CreateListNode(3);
ListNode* pNode5 = CreateListNode(5);
ConnectListNodes(pNode1, pNode3);
ConnectListNodes(pNode3, pNode5);
ListNode* pNode2 = CreateListNode(2);
ListNode* pNode4 = CreateListNode(4);
ListNode* pNode6 = CreateListNode(6);
ConnectListNodes(pNode2, pNode4);
ConnectListNodes(pNode4, pNode6);
ListNode* pMergedHead = Test("Test1", pNode1, pNode2);
DestroyList(pMergedHead);
}
void Test2()
{
ListNode* pNode1 = CreateListNode(1);
ListNode* pNode3 = CreateListNode(3);
ListNode* pNode5 = CreateListNode(5);
ConnectListNodes(pNode1, pNode3);
ConnectListNodes(pNode3, pNode5);
ListNode* pNode2 = CreateListNode(1);
ListNode* pNode4 = CreateListNode(3);
ListNode* pNode6 = CreateListNode(5);
ConnectListNodes(pNode2, pNode4);
ConnectListNodes(pNode4, pNode6);
ListNode* pMergedHead = Test("Test2", pNode1, pNode2);
DestroyList(pMergedHead);
}
void Test3()
{
ListNode* pNode1 = CreateListNode(1);
ListNode* pNode2 = CreateListNode(2);
ListNode* pMergedHead = Test("Test3", pNode1, pNode2);
DestroyList(pMergedHead);
}
void Test4()
{
ListNode* pNode1 = CreateListNode(1);
ListNode* pNode3 = CreateListNode(3);
ListNode* pNode5 = CreateListNode(5);
ConnectListNodes(pNode1, pNode3);
ConnectListNodes(pNode3, pNode5);
ListNode* pMergedHead = Test("Test4", pNode1, NULL);
DestroyList(pMergedHead);
}
void Test5()
{
ListNode* pMergedHead = Test("Test5", NULL, NULL);
}
int main()
{
Test1();
Test2();
Test3();
Test4();
Test5();
return 0;
}