单链公共节点查询：
给定两个单向链表，计算两个链表的第一个公共节点；若没有公共节点，返回空。
程序实现：
1 /************************************ 2 File Name:ListFirstSameNode.cpp 3 Author: godfrey 4 Created Time: 2016/04/29 5 *************************************/ 6 #include <iostream> 7 #include <cstdio> 8 #include <cstdlib> 9 using namespace std; 10 11 typedef struct tagSNode{ 12 int value; 13 tagSNode* pNext; 14 15 tagSNode(int v):value(v),pNext(NULL) {} 16 }SNode; 17 //打印链表 18 void Print(SNode* pHead){ 19 SNode* p = pHead->pNext; 20 while(p){ 21 cout<<p->value<<" "; 22 p = p->pNext; 23 } 24 cout<<endl; 25 } 26 //删除分配结点空间 27 void Destroy(SNode* pHead){ 28 SNode* p; 29 while(pHead){ 30 p = pHead->pNext; 31 delete pHead; 32 pHead = p; 33 } 34 } 35 36 //计算链表长度 37 int CalcListLength(SNode* p){ 38 int nLen = 0; 39 while(p){ 40 p = p->pNext; 41 nLen++; 42 } 43 return nLen; 44 } 45 46 //找到链表第一个公共节点 47 SNode* FindListFirstSameNode(SNode* p1Head,SNode* p2Head){ 48 //指向第一个有效节点 49 SNode* p1 = p1Head->pNext; 50 SNode* p2 = p2Head->pNext; 51 //定义长度长短的链表，默认p1长 52 SNode* pLonger = p1; 53 SNode* pShorter = p2; 54 //计算链表长度 55 int p1Len = CalcListLength(p1); 56 int p2Len = CalcListLength(p2); 57 int LenDif = p1Len-p2Len; 58 //更改长度长的链表 59 if(p1Len<p2Len){ 60 pLonger = p2; 61 pShorter = p1; 62 LenDif = p2Len-p1Len; 63 } 64 //空转LenDif次 65 for(int i=0;i<LenDif;i++){ 66 pLonger = pLonger->pNext; 67 } 68 //齐头并进，找到第一个公共节点，找不到返回NULL 69 while(pLonger && pShorter){ 70 if(pLonger == pShorter) 71 return pShorter; 72 pLonger = pLonger->pNext; 73 pShorter = pShorter->pNext; 74 } 75 return NULL; 76 } 77 78 int main() 79 { 80 int data[] = {1,2,3,4,5,6,7,8,9}; 81 SNode* p1Head = new SNode(0); 82 SNode* p2Head = new SNode(0); 83 int size = sizeof(data)/sizeof(int); 84 for(int i=size-1;i>=0;i--){ 85 SNode* p = new SNode(data[i]); 86 p->pNext = p1Head->pNext; 87 p1Head->pNext = p; 88 if((i<=size-1)&& (i>=3)){ 89 p->pNext = p2Head->pNext; 90 p2Head->pNext = p; 91 } 92 } 93 94 Print(p1Head); 95 Print(p2Head); 96 SNode* q = FindListFirstSameNode(p1Head,p2Head); 97 cout<<q->value<<" "<<q->pNext<<endl; 98 Destroy(p1Head); 99 Destroy(p2Head); 100 return 0; 101 }
运行结果：
