标签：自己 思考 assert 代码 inf return 知识 判断 code
前言：
深知自己对于这个知识点掌握的不是很好，故好好思考，并记录下思考后的成果。
既然已经分析清楚，那么代码就很好实现了。。。
Node* IsHaveCrossNode(Node* head1,Node* head2)
{
assert(head1);
assert(head2);
Node* meetNode1 = IsCircle(head1);
Node* meetNode2 = IsCircle(head2);
//排除第1种情况
if (meetNode1 == NULL || meetNode2 == NULL)
{
return NULL;
}
//说明两个链表都带环
//根据相遇点排除第2种情况
Node* cur1 = meetNode1->_next;
while (cur1 != meetNode1 && cur1 != meetNode2)
{
cur1 = cur1->_next;
}
if (cur1 != meetNode2)
{
return NULL;
}
//区分第3和第4种情况（需要求出两个入口点）
Node* entry1 = GetEntryNode(head1, meetNode1);
Node* entry2 = GetEntryNode(head2, meetNode2);
//第3种情况(转化为求两个链表的交点,链表不带环时)
if (entry1 == entry2)
{
entry1->_next = NULL;
entry2->_next = NULL;
Node* meet = IsMeet(head1, head2);
return meet;
}
//第4种情况（有两个入口点，返回一个即可）
return entry1;
}
//判断一个链表是否带环 //思路：快慢指针,返回相遇点 Node* IsCircle(Node* head) { if (head == NULL) { return NULL; } Node* pFast = head; Node* pSlow = head; //快指针一次走两步，慢指针一次走一步 while (pFast && pFast->_next) { pFast = pFast->_next->_next; pSlow = pSlow->_next; if (pFast == pSlow) { break; } } if (pFast && pFast->_next) { return pFast; } return NULL; } Node* GetEntryNode(Node* head, Node* meetNode) { assert(head && meetNode); Node* p1 = head; Node* p2 = meetNode; while (p1 != p2) { p1 = p1->_next; p2 = p2->_next; } return p1; } //判断是否相交，判断尾节点 //若相交，则返回交点 Node* IsMeet(Node* head1,Node* head2) { assert(head1 && head2); Node* cur1 = head1; int count1 = 0; Node* cur2 = head2; int count2 = 0; while (cur1->_next) { ++count1; cur1 = cur1->_next; } while (cur2->_next) { count2++; cur2 = cur2->_next; } if (cur1 != cur2) { return NULL;//说明没有交点 } int D_val = count2 - count1; if (D_val < 0) { D_val = -D_val; } // cur1 = head1; cur2 = head2; if (count1 < count2) { //让head2链表先走D_val长度 while (cur2 && D_val--) { cur2 = cur2->_next; } while (cur2 && cur1 != cur2) { cur1 = cur1->_next; cur2 = cur2->_next; } if (cur1 == cur2) { return cur1; } } else { //让head1链表先走D_val长度 while (cur1 && D_val--) { cur1 = cur1->_next; } while (cur1 && cur1 != cur2) { cur1 = cur1->_next; cur2 = cur2->_next; } if (cur1 == cur2) { return cur1; } } return NULL; }
标签：自己 思考 assert 代码 inf return 知识 判断 code
原文地址：https://www.cnblogs.com/daanshenghuo/p/12489386.html
