定义一个函数，输入一个链表的头结点，反转该链表并输出反转后链表的头结点。
struct ListNode { int m_nValue; ListNode* m_pNext; }; ListNode* ReverseList(ListNode* pHead) { ListNode* pReversedHead = NULL; ListNode* pNode = pHead; ListNode* pPrev = NULL; while(pNode != NULL) { ListNode* pNext = pNode->m_pNext; if(pNext == NULL) pReversedHead = pNode; pNode->m_pNext = pPrev; pPrev = pNode; pNode = pNext; } return pReversedHead; } 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(ListNode* pHead) { printf("The original list is: \n"); PrintList(pHead); ListNode* pReversedHead = ReverseList(pHead); printf("The reversed list is: \n"); PrintList(pReversedHead); return pReversedHead; } void Test1() { ListNode* pNode1 = CreateListNode(1); ListNode* pNode2 = CreateListNode(2); ListNode* pNode3 = CreateListNode(3); ListNode* pNode4 = CreateListNode(4); ListNode* pNode5 = CreateListNode(5); ConnectListNodes(pNode1, pNode2); ConnectListNodes(pNode2, pNode3); ConnectListNodes(pNode3, pNode4); ConnectListNodes(pNode4, pNode5); ListNode* pReversedHead = Test(pNode1); DestroyList(pReversedHead); } void Test2() { ListNode* pNode1 = CreateListNode(1); ListNode* pReversedHead = Test(pNode1); DestroyList(pReversedHead); } void Test3() { Test(NULL); } int main() { Test1(); Test2(); Test3(); return 0; }
