pat 1032. Sharing (25)

建两条双向链表，然后从后向前比较

#include<stdio.h>#define SIZE 100000struct list{    int add;    struct list *next, *forward;    char key;};struct Node{    int add,next;    char key;}node[SIZE];int main(){    freopen("1.in", "r", stdin);    int n, starta, startb;    scanf("%d%d%d", &starta, &startb, &n);    int i;    for (i = 0; i < n; i++)        scanf("%d %c %d", &node[i].add, &node[i].key, &node[i].next);    int next;    struct list *ha,*ta;    ha = new struct list;    ha->next = NULL;    ta = ha;    next = starta;    while (next != -1){        for (i = 0; i < n;i++)            if (node[i].add == next){                struct list *nd = new struct list;                nd->add = next;                nd->key = node[i].key;                nd->next = NULL;                nd->forward = ta;                if (ta == ha)                    ha->next = nd;                ta->next = nd;                ta = nd;                next = node[i].next;            }    }    struct list *hb, *tb;    hb = new struct list;    hb->next = NULL;    tb = hb;    next = startb;    while (next != -1){        for (i = 0; i < n; i++)            if (node[i].add == next){                struct list *nd = new struct list;                nd->add = next;                nd->key = node[i].key;                nd->next = NULL;                nd->forward = tb;                if (tb == hb)                    hb->next = nd;                tb->next = nd;                tb = nd;                next = node[i].next;            }    }    struct list *pa, *pb;    pa = ta;    pb = tb;    while (pa != ha&&pb != hb){        if (pa->add != pb->add)            break;        pa = pa->forward;        pb = pb->forward;    }    if (pa->next)        printf("%05d\n", pa->next->add);    else printf("-1\n");    return 0;}