Hdu1054 strategic game (binary matching)

Question:

Give you a graph. When each vertex is overwritten, the adjacent vertex is also overwritten.

Minimum number to overwrite all vertices

Ideas:

I did this question when I learned the tree-like DP, which is definitely faster than the Binary Graph ..

Click the bipartite graph. n = 1500. Use Hungary and HK to calculate it.

Go to Hungary first .. 624 Ms

/* ***********************************************Author        :devilCreated Time  :2016/5/17 11:42:42************************************************ */#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#include <vector>#include <queue>#include <set>#include <map>#include <string>#include <cmath>#include <stdlib.h>using namespace std;const int N=1510;int link[N];bool vis[N];vector<int>eg[N];bool dfs(int u){    for(int i=0;i<eg[u].size();i++)    {        int v=eg[u][i];        if(!vis[v])        {            vis[v]=1;            if(link[v]==-1||dfs(link[v]))            {                link[v]=u;                return 1;            }        }    }    return 0;}int main(){    //freopen("in.txt","r",stdin);    int n,x,y,k;    while(~scanf("%d",&n))    {        memset(link,-1,sizeof(link));        for(int i=0;i<n;i++)            eg[i].clear();        for(int i=0;i<n;i++)        {            scanf("%d:(%d)",&x,&k);            while(k--)            {                scanf("%d",&y);                eg[x].push_back(y);                eg[y].push_back(x);            }        }        int ans=0;        for(int i=0;i<n;i++)        {            memset(vis,0,sizeof(vis));            ans+=dfs(i);        }        printf("%d\n",ans/2);    }    return 0;}

Then my big HK--, 327 Ms

/* ***********************************************Author        :devilCreated Time  :2016/5/17 11:46:38************************************************ */#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#include <vector>#include <queue>#include <set>#include <map>#include <string>#include <cmath>#include <stdlib.h>using namespace std;const int N=1510;const int inf=0x3f3f3f3f;vector<int>eg[N];int n;int mx[N],my[N];int dx[N],dy[N],dis;bool vis[N];bool bfs(){    queue<int>q;    dis=inf;    memset(dx,-1,sizeof(dx));    memset(dy,-1,sizeof(dy));    for(int i=0;i<n;i++)        if(mx[i]==-1)        {            q.push(i);            dx[i]=0;        }    while(!q.empty())    {        int u=q.front();        q.pop();        if(dx[u]>dis) break;        for(int i=0;i<eg[u].size();i++)        {            int v=eg[u][i];            if(dy[v]==-1)            {                dy[v]=dx[u]+1;                if(my[v]==-1) dis=dy[v];                else                {                    dx[my[v]]=dy[v]+1;                    q.push(my[v]);                }            }        }    }    return dis!=inf;}bool dfs(int u){    for(int i=0;i<eg[u].size();i++)    {        int v=eg[u][i];        if(!vis[v]&&dy[v]==dx[u]+1)        {            vis[v]=1;            if(my[v]!=-1&&dy[v]==dis) continue;            if(my[v]==-1||dfs(my[v]))            {                my[v]=u;                mx[u]=v;                return 1;            }        }    }    return 0;}int MaxMatch(){    int ans=0;    memset(mx,-1,sizeof(mx));    memset(my,-1,sizeof(my));    while(bfs())    {        memset(vis,0,sizeof(vis));        for(int i=0;i<n;i++)            if(mx[i]==-1&&dfs(i))                ans++;    }    return ans;}int main(){    //freopen("in.txt","r",stdin);    int x,y,k;    while(~scanf("%d",&n))    {        for(int i=0;i<n;i++)            eg[i].clear();        for(int i=0;i<n;i++)        {            scanf("%d:(%d)",&x,&k);            while(k--)            {                scanf("%d",&y);                eg[x].push_back(y);                eg[y].push_back(x);            }        }        printf("%d\n",MaxMatch()/2);    }    return 0;}

 

Hdu1054 strategic game (binary matching)