poj 2513 -- Colored Sticks ( Trie + 并查集 + 欧拉 ）

WA了很久的一道题了，今天终于过了

判断条件有两个

1 、出现次数为奇数的颜色<=2 

2 、判断图是否连通

用Trie处理效率较高，判断连通可以将颜色映射成数字用并查集

# include <cstdio># include <iostream># include <set># include <map># include <vector># include <list># include <queue># include <stack># include <cstring># include <string># include <cstdlib># include <cmath># include <algorithm>using namespace std ;struct Dic{    int id ;    int vis ;    int next [ 30 ] ;} dic [ 3000000 ] ;int cnt ;int pre [ 510000 ] ;int top ;int find ( int x ){    if ( pre [ x ] != x )        pre [ x ] = find ( pre [ x ] ) ;    return pre [ x ] ;}void Union ( int x , int y ){    pre [ find ( x ) ] = find ( y ) ;}int addword ( char t [ ] ){    int num = 0 ;    int len = strlen ( t ) ;    for ( int i = 0 ; i < len ; i ++ )    {        int tmp = t [ i ] - 'a' ;        if ( dic [ num ] . next [ tmp ] == 0 )        {            dic [ num ] . next [ tmp ] = cnt ;            num = cnt ++ ;        }        else            num = dic [ num ] . next [ tmp ] ;    }    dic [ num ] . vis ++ ;    if ( dic [ num ] . vis == 1 )    {        dic [ num ] . id = top ++ ;    }    return dic [ num ] . id ;}int findword ( char * t ){    int num = 0 ;    int len = strlen ( t ) ;    for ( int i = 0 ; i < len ; i ++ )    {        int tmp = t [ i ] - 'a' ;        if ( dic [ num ] . next [ tmp ] == 0 )            return false ;        else            num = dic [ num ] . next [ tmp ] ;    }    return dic [ num ] . id ;}int main ( ){    cnt = 1 ;    top = 1 ;    for ( int i = 1 ; i < 510000 ; i ++ )        pre [ i ] = i ;    char s [ 12 ] , t [ 13 ] ;    while ( scanf ( "%s%s" , s , t ) != EOF )    {        int x = addword ( s ) ;        int y = addword ( t ) ;        Union ( x , y ) ;    }    int flag = 1 ;    int sum = 0 ;    for ( int i = 1 ; i < cnt ; i ++ )    {        if ( dic [ i ] . vis % 2 )            sum ++ ;    }    if ( sum > 2 )        flag = 0 ;    if ( flag == 0 )        cout << "Impossible" << endl ;    else    {        for ( int i = 2 ; i < top ; i ++ )            if ( find ( i ) != find ( 1 ) )                flag = 0 ;        if ( flag )            cout << "Possible" << endl ;        else            cout << "Impossible" << endl ;    }}