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  • [欧拉] poj 2513 Colored Sticks

    主题链接:

    http://poj.org/problem?

    id=2513

    Colored Sticks
    Time Limit: 5000MS   Memory Limit: 128000K
    Total Submissions: 30955   Accepted: 8159

    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 red
    red violet
    cyan blue
    blue magenta
    magenta cyan
    

    Sample Output

    Possible

    Hint

    Huge input,scanf is recommended.

    Source

    [Submit]   [Go Back]   [Status]   [Discuss]

    题目意思:

    有n条木棒。每条木棒两端有两种颜色,求这些木棒是否能能在一起,使得前一个木棒的后端颜色和前一个木棒的前端颜色一样。

    解题思路:

    欧拉通路+字典树+并查集

    注意是无向边。注意要推断连通性。直接用map映射会超时,自己写字典树。

    代码:

    //#include<CSpreadSheet.h>
    
    #include<iostream>
    #include<cmath>
    #include<cstdio>
    #include<sstream>
    #include<cstdlib>
    #include<string>
    #include<string.h>
    #include<cstring>
    #include<algorithm>
    #include<vector>
    #include<map>
    #include<set>
    #include<stack>
    #include<list>
    #include<queue>
    #include<ctime>
    #include<bitset>
    #include<cmath>
    #define eps 1e-6
    #define INF 0x3f3f3f3f
    #define PI acos(-1.0)
    #define ll __int64
    #define LL long long
    #define lson l,m,(rt<<1)
    #define rson m+1,r,(rt<<1)|1
    #define M 1000000007
    //#pragma comment(linker, "/STACK:1024000000,1024000000")
    using namespace std;
    
    #define Maxn 550000
    
    int dei[Maxn],a[Maxn],cnt,la;
    
    struct Node
    {
        struct Node * next[30];
        int nu;
    }node[Maxn*15],root;
    
    
    int Insert(char *a)
    {
        Node * p=&root;
    
        while(*a)
        {
            if(p->next[*a-'a'+1]==NULL)
            {
                node[++la].nu=0;
                memset(node[la].next,NULL,sizeof(node[la].next));
                p->next[*a-'a'+1]=&node[la];
            }
            p=p->next[*a-'a'+1];
            a++;
        }
        if(!p->nu)
            p->nu=++cnt;
        return p->nu;
    
    }
    
    int Find(int x)
    {
        int temp=x;
        while(x!=fa[x])
            x=fa[x];
        while(fa[temp]!=x)
        {
            int cur=fa[temp];
            fa[temp]=x;
            temp=cur;
        }
        return x;
    }
    void Unio(int a,int b)
    {
        a=Find(a),b=Find(b);
        if(a!=b)
            fa[a]=b;
    }
    int main()
    {
    
       memset(dei,0,sizeof(dei));
       string a,b;
       char sa[15],sb[15];
       cnt=la=0;
       for(int i=1;i<=Maxn-5000;i++)
            fa[i]=i;
    
       memset(root.next,NULL,sizeof(root.next));
       root.nu=0;
    
       while(~scanf("%s%s",sa+1,sb+1))
       {
           int a=Insert(sa+1);
           int b=Insert(sb+1);
    
           dei[a]++,dei[b]++;
           Unio(a,b);
       }
       bool ans=true;
       int nui=0,nuo=0,la=-1;
    
       for(int i=1;i<=cnt;i++)
       {
           if(la==-1)
                la=Find(i);
           else if(la!=Find(i))
           {
               ans=false;
               break;
           }
           if(dei[i]&1)
                nui++;
       }
       if(!ans||nui>2||nui==1)
            printf("Impossible
    ");
       else
            printf("Possible
    ");
       //system("pause");
    
        return 0;
    }
    
    


    版权声明:本文博客原创文章,博客,未经同意,不得转载。

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  • 原文地址:https://www.cnblogs.com/hrhguanli/p/4629539.html
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