hdu 4888

网络流建模，建模不难，难在找环；

#include<cstdio>
#include<algorithm>
#include<vector>
#include<queue>
#include<cstring>
#define inf 1<<30
#define maxn 2100
using namespace std;

struct edge
{
    int from,to,cap,flow;
    edge(int from,int to,int cap,int flow):from(from),to(to),cap(cap),flow(flow) {}
};

struct dinic
{
    int n,m,s,t;
    vector<edge>edges;
    vector<int>g[maxn];
    bool vis[maxn];
    int d[maxn];
    int cur[maxn];
    bool ishuan[maxn];
    int jie[550][550];

    void init(int n)
    {
        this->n=n;
        for(int i=0; i<n; i++)
            g[i].clear();
        edges.clear();
        memset(d,0,sizeof d);
        memset(cur,0,sizeof cur);
    }

    void addedge(int from,int to,int cap)
    {
        edges.push_back(edge(from,to,cap,0));
        edges.push_back(edge(to,from,0,0));
        m=edges.size();
        g[from].push_back(m-2);
        g[to].push_back(m-1);
    }
queue<int >q;
    bool bfs()
    {
        memset(vis,0,sizeof vis);
        while(!q.empty()) q.pop();
        q.push(s);
        d[s]=0;
        vis[s]=1;
        while(!q.empty())
        {
            int x=q.front();
            q.pop();
            for(int i=0; i<g[x].size(); i++)
            {
                edge& e=edges[g[x][i]];
                if(!vis[e.to]&&e.cap>e.flow)
                {
                    vis[e.to]=1;
                    d[e.to]=d[x]+1;
                    q.push(e.to);
                }
            }
        }
        return vis[t];
    }

    int dfs(int x,int a)
    {
        if(x==t||a==0)return a;
        int flow=0,f;
        for(int &i=cur[x]; i<g[x].size(); i++)
        {
            edge& e=edges[g[x][i]];
            if(d[x]+1==d[e.to]&&(f=dfs(e.to,min(a,e.cap-e.flow)))>0)
            {
                e.flow+=f;
                edges[g[x][i]^1].flow-=f;
                flow+=f;
                a-=f;
                if(a==0)break;
            }
        }
        return flow;
    }

    int maxflow(int s,int t)
    {
        this->s=s;
        this->t=t;
        int flow=0;

        while(bfs())
        {
            memset(cur,0,sizeof cur);
            flow+=dfs(s,inf);
        }
        return flow;
    }

    bool panhuan(int v,int f)
    {
        if(ishuan[v])return 1;
        ishuan[v]=1;
        for(int i=0;i<g[v].size();i++)
        {
            if(g[v][i]==(f^1))continue;
            int tmp=g[v][i];
            if(edges[tmp].to==t||edges[tmp].to==s)continue;
            if(edges[tmp].cap-edges[tmp].flow>0)
            {
                if(panhuan(edges[tmp].to,tmp))return 1;
            }
        }
        ishuan[v]=0;
        return 0;
    }

    bool haofang(int x)
    {
        memset(ishuan,0,sizeof ishuan);
        for(int i=1; i<=x; i++)
        {
            if(panhuan(i,-1))return 1;
        }
        return 0;
    }

    void getans(int x,int y)
    {
        for(int i=0;i<edges.size();i++)
        {
            if(edges[i].cap&&edges[i].from>0&&edges[i].from<=x)
            {
                jie[edges[i].from][edges[i].to-x]=edges[i].flow;
            }
        }
    }
};

int hang[550];
int lie[550];

dinic solve;

int main()
{
    int n,m,k;
    while(scanf("%d%d%d",&n,&m,&k)!=EOF)
    {
        int sum_hang=0,sum_lie=0;
        for(int i=1; i<=n; i++)
        {
            scanf("%d",&hang[i]);
            sum_hang+=hang[i];
        }
        for(int i=1; i<=m; i++)
        {
            scanf("%d",&lie[i]);
            sum_lie+=lie[i];
        }
        if(sum_hang!=sum_lie)
        {
            puts("Impossible");
            continue;
        }
        solve.init(n+m+2);
        solve.s=0;
        solve.t=n+m+1;
        for(int i=1;i<=n;i++)
        {
            solve.addedge(solve.s,i,hang[i]);
            for(int j=1;j<=m;j++)
                solve.addedge(i,j+n,k);
        }
        for(int i=1;i<=m;i++)
            solve.addedge(i+n,solve.t,lie[i]);
        int ans=solve.maxflow(solve.s,solve.t);
        if(ans!=sum_hang)
            puts("Impossible");
        else
        {
            if(solve.haofang(n))
                puts("Not Unique");
            else
            {
                puts("Unique");
                solve.getans(n,m);
                for(int i=1;i<=n;i++)
                {
                    for(int j=1;j<m;j++)
                        printf("%d ",solve.jie[i][j]);
                    printf("%d
",solve.jie[i][m]);
                }
            }
        }
    }
    return 0;
}