poj2513Colored Sticks(欧拉通路+字典树+并查集)

#include<stdio.h>
typedef struct nn
{
    int flag;
    int indx;
    struct nn *next[26];
}node;
node *builde()
{
    node *p=new node;
    p->flag=0;
    for(int i=0;i<26;i++)
    p->next[i]=NULL;
    return p;
}
node *root;
int jdn;//计算顶点为奇数的个数
int insert(char str[],int n)
{
    node *p=root;
    for(int i=0;str[i]!='\0';i++)
    {
        if(p->next[str[i]-'a']==NULL)
        p->next[str[i]-'a']=builde();
        p=p->next[str[i]-'a'];
    }
    if(p->flag==0)
    p->indx=n;
    p->flag++;
    if((p->flag)%2)jdn++;else jdn--;
    return p->indx;
}

int fath[5100000],dn;//dn为边数和点数之差
int findfather(int x)
{
    if(x!=fath[x])
    fath[x]=findfather(fath[x]);
    return fath[x];
}
void set(int a,int b)
{
    a=findfather(a);
    b=findfather(b);
    if(a!=b)
    {
        dn--; fath[a]=b;
    }
}
int main()
{
    char c1[1000],c2[1000];
    int n=0,a,b;
    dn=0; jdn=0;
    root=builde();
    while(scanf("%s%s",c1,c2)>0)
    {
        a=insert(c1,n+1);
        if(a==n+1)
        {
            dn++; n++; fath[n]=n;
        }
        b=insert(c2,n+1);
        if(b==n+1)
        {
            dn++; n++; fath[n]=n;
        }
        set(a,b);
    }
    if((jdn==2||jdn==0)&&dn==1||n==0)
    printf("Possible\n");
    else
    printf("Impossible\n");
}