C++博客-Dreams-随笔分类-并查集

并查集的初级应用及进阶

DreamSky — Wed, 15 Apr 2009 05:46:00 GMT

摘要: 并查集的初级应用及进阶一、精华精华提炼1：内容：并查集就是树的孩子表示法的应用。解释：对于下图所示树，它的孩子表示法为： &... 阅读全文

DreamSky 2009-04-15 13:46 发表评论

hdu 1558 Segment set

DreamSky — Tue, 14 Apr 2009 12:22:00 GMT

摘要: http://acm.hdu.edu.cn/showproblem.php?pid=1558 //1270982 2009-04-14 20:14:31 Accepted 1558 390MS 264K 2589 B C++ no way #include阅读全文

DreamSky 2009-04-14 20:22 发表评论

hdu 1272 小希的迷宫

DreamSky — Sun, 12 Apr 2009 09:08:00 GMT

http://acm.hdu.edu.cn/showproblem.php?pid=1272

//1264198 2009-04-12 16:58:37 Accepted 1272 31MS 1096K 1573 B C++ no way
#include<iostream>
using namespace std;
struct Node
{
    long parent;
    long hight;
};
Node polong[100001];
bool visited[100001];//标记某点出现过
long find(long x) //查找根
{
    while(x != polong[x].parent)
        x = polong[x].parent;
    return x;
}

void merge(long a,long b)//合并
{
    if(polong[a].hight == polong[b].hight)
    {
        polong[a].parent = b;
        polong[b].hight += 1;
    }
    else if(polong[a].hight > polong[b].hight)
        polong[b].parent = a;
    else
        polong[a].parent = b;
}

long main()
{
    long maxn,minn,a,b,sign,i;
    while(scanf("%ld%ld",&a,&b)!=EOF)
    {
        if(a==-1 && b==-1)
            break;
        if(a==0 && b==0)
        {
            cout<<"Yes"<<endl;
            continue;
        }
        for(i=1;i<=100000;i++)//注意注意
        {
            polong[i].parent = i;
            polong[i].hight = 1;
            visited[i] = 0;
        }

        maxn = 0;
        minn = 100000;
        sign = 0;

        do{
            if(a > maxn)     maxn = a;
            if(b > maxn)    maxn = b;
            if(minn > a)    minn = a;
            if(minn > b)    minn = b;
            visited[a] = 1;
            visited[b] = 1;
            a = find(a);
            b = find(b);
            if(a == b) //根相同表示有回路~
            {
                sign = -1;
                break;
            }
            else
                merge(a,b);

            scanf("%ld%ld",&a,&b);
            if(a==0 && b==0)
                break;
        }while(1);

        if(sign == -1) //还未输入完
        {
            do{
                  scanf("%ld%ld",&a,&b);
                  if(a==0 && b==0)
                      break;
            }while(1);
        }

        if(sign == 0) //没有回路，查看是否都在一个集合
        {
            for(i=minn;i<=maxn;i++)
                if(visited[i] == 1 && polong[i].parent == i)
                    sign ++;
        }

        if(sign == 1)
            cout<<"Yes"<<endl;
        else
            cout<<"No"<<endl;
    }
    return 0;
}

DreamSky 2009-04-12 17:08 发表评论

hdu 1232 畅通工程

DreamSky — Sun, 12 Apr 2009 03:34:00 GMT

http://acm.hdu.edu.cn/showproblem.php?pid=1232

#include<iostream>
#include<set>
using namespace std;
struct Node
{
    int parent;
    int hight;
};
Node village[1001];

int find(int x) //寻找父亲
{
    while(x != village[x].parent)
        x = village[x].parent;
    return x;
}

void merge(int a,int b)
{
    if(village[a].hight == village[b].hight)//树高一样
    {
            village[b].parent = a;
            village[a].hight += 1;
    }
    else if(village[a].hight > village[b].hight) //矮树并入高树
    {
        village[b].parent = a;//并入a
    }
    else
    {
        village[a].parent = b;//并入b
    }
}
int main()
{
    int n;
    while(scanf("%d",&n) && n)
    {
        int m,i,j,a,b,sum = 0;

        for(i=1;i<=n;i++)
        {
            village[i].parent = i;
            village[i].hight = 1;
        }
        scanf("%d",&m);
        while(m--)
        {
            scanf("%d%d",&a,&b);
            a = find(a); //寻找a的根节点
            b = find(b); //寻找b的根节点
            if(a!=b) //根节点不一样才合并
                merge(a,b);
        }
        set<int>S;
        for(i=1;i<=n;i++) //查找有多少个集合
            S.insert(find(i));
        cout<<S.size()-1<<endl;
    }
    return 0;
}

DreamSky 2009-04-12 11:34 发表评论