POJ 2513 Colored Sticks

解题思路:trie树+并查集（判断是否属于同一集合）+欧拉通路判断

#include <iostream>
using namespace std;
#define MAXN 5000001
#define MAXM 500001
char ch1[11],ch2[11],trie[MAXN];
int size,first[MAXN],next[MAXN],place[MAXN];
int n,root[MAXM],deg[MAXM];

int find(int x)
{
    if(root[x]!=x)root[x]=find(root[x]);
    return root[x];
}
int insert(char ch[])
{
    int i, t, p=0,l=strlen(ch);
    for(i=0;i<l;i++)
    {
        t=first[p];
        while (t&&trie[t]!=ch[i])t=next[t];
        if(!t)
        {
            trie[++size]=ch[i],next[size]=first[p];
            first[p]=size,first[size]=0,p=size;
        }
        else p=t;
    }
    if(!place[p])place[p]=++n;
    return place[p];
}
int main()
{
    int i,r1,r2,r,odd;
    bool IsOk;
    for(i=0;i<MAXM;i++)root[i]=i;
    size=n=0;
    while(scanf("%s%s", ch1, ch2)!=EOF)
    {
        r1=insert(ch1),r2=insert(ch2);
        deg[r1]++,deg[r2]++;
        r1=find(r1),r2=find(r2);
        if(r1!=r2)root[r2]=r1;
    }
    for (IsOk=i=1,r=find(1),odd=0;i<n&&IsOk;i++)
    {
        if(root[i]==i&&i!=r)IsOk=false;
        if(deg[i]%2){odd++;if(odd>2)IsOk=false;}
    }
    IsOk?printf("Possible\n"):printf("Impossible\n");
    return 0;
}