判断两个链表是否相汇，可以通过将第一个链表的尾部与第二个链表的头部相连接，如果链表形成了环，则说明链表相汇了。
/*
* 两个链表是否公共结点
*/
#include<iostream>
#include<ctime>
#include<cstdlib>
#include<cstdio>
using namespace std;
typedef struct node* link;
typedef struct node{
int value;
link next;
node(){
value=-1;
next=NULL;
}
node(int v){
value=v;
next=NULL;
}
}Node;
void GenerateList(link& head1,link& head2){
int n=rand()%100+1;
head1=new Node();
head2=new Node();
link p1=head1,p2=head2;
for(int i=0;i<n;i++){
int x=rand()%100+1;
p1->next=new Node(x);
p1=p1->next;
}
int m=rand()%100+1;
for(int i=0;i<m;i++){
int x=rand()%100+1;
p2->next=new Node(x);
p2=p2->next;
}
p1->next=p2; //if this statement is deleted, the two lists will have no common points;
printf("the random common point's address:%d\n",p2);
int k=rand()%100+1;
for(int i=0;i<k;i++){
int x=rand()%100+1;
p2->next=new Node(x);
p2=p2->next;
}
head1->value=n+k+1;
head2->value=m+k;
}
bool FindCircle(link head){
link p=head;
while(p->next!=NULL){
p=p->next;
if(p==head){
return true;
}
}
return false;
}
int main(){
srand((unsigned)time(NULL));
link head1=NULL,head2=NULL;
GenerateList(head1,head2);
// connect tail of list1 to the head of list2
link p=head1;
while(p->next!=NULL) p=p->next;
p->next=head2;
//judge whether there exists a circle
if(FindCircle(head2)){
if(head1->value<head2->value){
int count=head2->value-head1->value;
while(count--){
head2=head2->next;
}
}else{
int count=head1->value-head2->value;
while(count--){
head1=head1->next;
}
}
while(head1!=head2){
head1=head1->next;
head2=head2->next;
}
printf("the common point's address:%d\n",head1);
}else{
printf("No common nodes\n");
}
return 0;
}