判断两条链表是否相交（公共部分）并找出相交处

  1 #include <iostream>
  2 
  3 using namespace std;
  4 
  5 struct Node
  6 {
  7     int val;
  8     Node* next;
  9     Node(int a = 0) :val(a), next(NULL) {}
 10 };
 11 
 12 void FindNode(Node* head1, Node* head2)
 13 {
 14     if (head1->next == NULL || head2->next == NULL)
 15         return;
 16     Node *p1, *p2;
 17     p1 = head1->next;
 18     p2 = head2->next;
 19     int size1, size2;//计算链表长度
 20     size1 = size2 = 1;
 21     while (p1->next || p2->next)
 22     {
 23         if (p1->next)
 24         {
 25             p1 = p1->next;
 26             size1++;            
 27         }
 28         if (p2->next)
 29         {
 30             p2 = p2->next;
 31             size2++;
 32         }
 33     }
 34     if (p1 != p2)
 35     {
 36         cout << "List1 and List2 have no commmon part!" << endl;
 37         return;
 38     }
 39     cout << "List1 and List2 have commmon part!" << endl;
 40     //重新遍历，找到交点
 41     p1 = head1->next;
 42     p2 = head2->next;
 43     for (int i = 0; i<(size1>size2 ? size1 - size2 : size2 - size1); ++i)//长的先遍历
 44     {
 45         if (size1 > size2)
 46             p1 = p1->next;
 47         else
 48             p2 = p2->next;
 49     }
 50     while (p1 != p2)
 51     {
 52         p1 = p1->next;
 53         p2 = p2->next;
 54     }
 55     cout << "相交部位为：addr：" << p1 << "  val:" << p1->val << endl;
 56 
 57 }
 58 
 59 void Test()
 60 {
 61     int a[] = { 1,2,3,4,5,6 };
 62     int b[] = { 4,5,6 };
 63     int c[] = { 7,8,9,10 };
 64     Node* head1 = new Node(-1);
 65     Node* head2 = new Node(-1);
 66     Node* p1 = head1;
 67     Node* p2 = head2;
 68 
 69     for (auto n : a)
 70     {
 71         Node* q = new Node(n);
 72         p1->next = q;
 73         p1 = q;
 74     }
 75     p1->next = NULL;
 76     for (auto n : b)
 77     {
 78         Node* q = new Node(n);
 79         p2->next = q;
 80         p2 = q;
 81     }
 82     p2->next = NULL;
 83 
 84     cout << "相交之前判断：" << endl;
 85     FindNode(head1, head2);
 86     cout << "***********************" << endl;
 87     for (auto n : c)
 88     {
 89         Node* q = new Node(n);
 90         p1->next = q;
 91         p1 = q;
 92         p2->next = q;
 93         p2 = q;
 94     }
 95     p1->next = NULL;
 96     p2->next = NULL;
 97 
 98     cout << "相交之后判断：" << endl;
 99     FindNode(head1, head2);
100     cout << "***********************" << endl;
101 }