题目:输入两个递增的排序的链表,合并这两个链表并使新链表中的节点仍然是
按照递增排序的。例如链表1链表2合并为链表3.
1 List1:1->3->5->7 2 3 List2:2->4->6->8 4 5 List3:1->2->3->4->5->6->7->8
链表结点定义如下:
1 struct ListNode 2 { 3 int m_nValue; 4 ListNode* m_pNext; 5 }
其实我们可以简单梳理下流程如下:
1.两个指针分别指向List1和List2的头结点。设为ptr1和ptr2
2.比较ptr1和ptr2结点的值,ptr1<ptr2则ptr1则是合并后的链表头结点
3.ptr1向后移动一个结点此时再比较 ptr1>ptr2则将ptr2的节点插入到头结点之后
4.当ptr1或者ptr2到达末尾时 比如ptr1到达List1结尾后 若此时ptr2还未到List2结尾
将ptr2插入到新排序的链表后面.
代码实现如下:
1 #include <iostream> 2 using namespace std; 3 4 struct ListNode 5 { 6 int data; 7 struct ListNode *next; 8 }; 9 10 struct ListNode* CreateList() 11 { 12 struct ListNode* Head,*p; 13 Head=(struct ListNode*)malloc(sizeof(ListNode)); 14 Head->data=0; 15 Head->next=NULL; 16 p=Head; 17 18 cout<<"Create List....(0-exit!)"<<endl; 19 while(true) 20 { 21 int Data; 22 cin>>Data; 23 if(Data!=0) 24 { 25 struct ListNode* NewNode; 26 NewNode=(struct ListNode*)malloc(sizeof(ListNode)); 27 NewNode->data=Data; 28 NewNode->next=NULL; 29 p->next=NewNode; 30 p=p->next; 31 } 32 else 33 { 34 break; 35 } 36 } 37 38 return Head->next; 39 } 40 41 void PrintList(struct ListNode* Head) 42 { 43 cout<<"The List is: "; 44 45 struct ListNode *p; 46 p=Head; 47 while(p!=NULL) 48 { 49 cout<<p->data<<" "; 50 p=p->next; 51 } 52 cout<<endl; 53 } 54 55 struct ListNode* Merge(ListNode* pHead1,ListNode* pHead2) 56 { 57 if(pHead1==NULL&&pHead2==NULL) 58 return NULL; 59 60 if(pHead1==NULL&&pHead2!=NULL) 61 return pHead2; 62 63 if(pHead1!=NULL&&pHead2==NULL) 64 return pHead1; 65 66 struct ListNode *ptr1,*ptr2,*MergeList,*newhead;; 67 68 ptr1=pHead1; 69 ptr2=pHead2; 70 71 if(ptr1->data>ptr2->data) 72 { 73 MergeList=ptr2; 74 ptr2=ptr2->next; 75 } 76 else 77 { 78 MergeList=ptr1; 79 ptr1=ptr1->next; 80 } 81 82 newhead=MergeList; 83 84 while(ptr1!=NULL&&ptr2!=NULL) 85 { 86 if(ptr1->data>ptr2->data) 87 { 88 MergeList->next=ptr2; 89 ptr2=ptr2->next; 90 MergeList=MergeList->next; 91 } 92 93 if(ptr1->data<ptr2->data) 94 { 95 MergeList->next=ptr1; 96 ptr1=ptr1->next; 97 MergeList=MergeList->next; 98 } 99 } 100 101 if(ptr1!=NULL) 102 { 103 while(ptr1!=NULL) 104 { 105 MergeList->next=ptr1; 106 ptr1=ptr1->next; 107 MergeList=MergeList->next; 108 } 109 MergeList->next=NULL; 110 } 111 if(ptr2!=NULL) 112 { 113 while(ptr2!=NULL) 114 { 115 MergeList->next=ptr2; 116 ptr2=ptr2->next; 117 MergeList=MergeList->next; 118 } 119 MergeList->next=NULL; 120 } 121 122 123 return newhead; 124 } 125 126 int main() 127 { 128 ListNode *List1,*List2,*MergeList; 129 List1=CreateList(); 130 PrintList(List1); 131 List2=CreateList(); 132 PrintList(List2); 133 MergeList=Merge(List1,List2); 134 PrintList(MergeList); 135 return 0; 136 }
运行截图:
