微软亚院之编程判断俩个链表是否相交

微软亚院之编程判断俩个链表是否相交

给出俩个单向链表的头指针，比如h1，h2，判断这俩个链表是否相交。

为了简化问题，我们假设俩个链表均不带环。

问题扩展：

1.如果链表可能有环列?

2.如果需要求出俩个链表相交的第一个节点列?

ANSWER:

struct Node {

int data;

int Node *next;

};

// if there is no cycle.

int isJoinedSimple(Node * h1, Node * h2) {

while (h1->next != NULL) {

h1 = h1->next;

}

while (h2->next != NULL) {

h2 = h2-> next;

}

return h1 == h2;

}

// if there could exist cycle

int isJoined(Node *h1, Node * h2) {

Node* cylic1 = testCylic(h1);

Node* cylic2 = testCylic(h2);

if (cylic1+cylic2==0) return isJoinedSimple(h1, h2);

if (cylic1==0 && cylic2!=0 || cylic1!=0 &&cylic2==0) return 0;

Node *p = cylic1;

while (1) {

if (p==cylic2 || p->next == cylic2) return 1;

p=p->next->next;

cylic1 = cylic1->next;

if (p==cylic1) return 0;

}

}

Node* testCylic(Node * h1) {

Node * p1 = h1, *p2 = h1;

while (p2!=NULL && p2->next!=NULL) {

p1 = p1->next;

p2 = p2->next->next;

if (p1 == p2) {

return p1;

}

}

return NULL;

}