POJ 2513 Colored Sticks

字典树存储，用并查集判连通， 欧拉回路判通路。

/*Accepted    59208K    422MS    C++    1191B    2012-08-02 11:38:21*/

#include<stdio.h>

#include<string.h>

#include<stdlib.h>

typedef struct

{

    int next[26];

    int cnt, ord;

}Trie;



Trie t[3000000];

int tp, op;

int p[510000];

char s1[20], s2[20], odd;

int find(int x)

{

    return p[x] == x ? x : (p[x] = find(p[x]));

}



int insert(char *x, int site)

{

    if(*x)

    {

        if(!t[site].next[*x - 'a'])

            t[site].next[*x - 'a'] = ++ tp;

        return insert(x + 1, t[site].next[*x - 'a']);

    }

    else{

        if(t[site].cnt & 1)

            odd --;

        else

            odd ++;

        if(!t[site].cnt)

            t[site].ord = ++ op;

        t[site].cnt ++;

        return t[site].ord;

    }

}



int judge()

{

    int i;

    for(i = 2; i <= op; i ++)

        if(find(i) != find(i - 1))

            return 0;

    return odd <= 2;

}



int main()

{

    int a, b, i;

    tp = op = 0;

    for(i = 0; i < 510000; i ++)

        p[i] = i;

    while(scanf("%s%s", s1, s2) == 2)

    {

        a = insert(s1, 0);

        b = insert(s2, 0);

        p[find(a)] = find(b);

    }

    if(judge())

        printf("Possible\n");

    else

        printf("Impossible\n");

    return 0;

}