Poj 2513 Colored Sticks（字典树+欧拉回路）

Colored Sticks

Time Limit: 5000MS Memory Limit: 128000KTotal Submissions: 31553 Accepted: 8339

Description

You are given a bunch of wooden sticks. Each endpoint of each stick is colored with some color. Is it possible to align the sticks in a straight line such that the colors of the endpoints that touch are of the same color?

Input

Input is a sequence of lines, each line contains two words, separated by spaces, giving the colors of the endpoints of one stick. A word is a sequence of lowercase letters no longer than 10 characters. There is no more than 250000 sticks.

Output

If the sticks can be aligned in the desired way, output a single line saying Possible, otherwise output Impossible.

Sample Input

blue redred violetcyan blueblue magentamagenta cyan

Sample Output

Possible

Hint

Huge input,scanf is recommended.

题意：

给定一些木棒，木棒两端都涂上颜色，求是否能将木棒首尾相接，连成一条直线，要求不同木棒相接的一边必须是相同颜色的

#include <iostream>#include <cstdio>#include <cstring>using namespace std;struct node{    int flag;    int no;    node *next[26];}*head;int degree[250050];int bin[150050];int color;int Search(char *s){    node *p=head;    node *q;    int i=0;    while(s[i]!='\0'){        if(p->next[ s[i]-'a' ]==NULL){            q=new node;            for(int j=0;j<26;j++){                q->next[j]=NULL;            }            q->flag=0;            q->no=0;            p->next[ s[i]-'a' ]=q;        }        p=p->next[ s[i]-'a' ];        i++;    }    if(p->flag)        return p->no;    else{        p->flag=1;        p->no=color++;        return p->no;    }}int Find(int x){    if(bin[x]==-1){        return x;    }    return x==bin[x]?x:Find(bin[x]);}void Merge(int x,int y){    int f1,f2;    f1=Find(x);    f2=Find(y);    if(f1!=f2)        bin[f1]=f2;}int main(){    char str1[15],str2[15];    memset(degree,0,sizeof(degree));    memset(bin,-1,sizeof(bin));    head=new node;    for(int i=0;i<26;i++){        head->next[i]=NULL;    }    head->flag=0;    head->no=0;    color=0;    while(scanf("%s%s",str1,str2)!=EOF){        int x=Search(str1);        int y=Search(str2);        degree[x]++;        degree[y]++;        Merge(x,y);    }    int odd=0,null=0;    int i;    for(i=0;i<color;i++){        if(degree[i]%2)            odd++;        if(bin[i]==-1)            null++;        if(odd==3)            break;        if(null==2)            break;    }    if(i==color)        cout<<"Possible"<<endl;    else        cout<<"Impossible"<<endl;    return 0;}