BZOJ3280: 小R的烦恼

  1 #include<cstdio>
  2 #include<cstdlib>
  3 #include<cmath>
  4 #include<cstring>
  5 #include<algorithm>
  6 #include<iostream>
  7 #include<vector>
  8 #include<map>
  9 #include<set>
 10 #include<queue>
 11 #include<string>
 12 #define inf 1000000000
 13 #define maxn 100000+5
 14 #define maxm 100000+5
 15 #define eps 1e-10
 16 #define ll long long
 17 #define pa pair<int,int>
 18 #define for0(i,n) for(int i=0;i<=(n);i++)
 19 #define for1(i,n) for(int i=1;i<=(n);i++)
 20 #define for2(i,x,y) for(int i=(x);i<=(y);i++)
 21 #define for3(i,x,y) for(int i=(x);i>=(y);i--)
 22 #define for4(i,x) for(int i=head[x],y=e[i].go;i;i=e[i].next,y=e[i].go)
 23 #define mod 1000000007
 24 using namespace std;
 25 inline int read()
 26 {
 27     int x=0,f=1;char ch=getchar();
 28     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
 29     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}
 30     return x*f;
 31 }
 32 int n,m,k,mincost,maxflow,tot=1,s,ss,t,sum,a[maxn],head[maxn],d[maxn],from[2*maxm];
 33 bool v[maxn];
 34 queue<int>q;
 35 struct edge{int from,go,next,v,c;}e[2*maxm];
 36 void add(int x,int y,int z,int w)
 37 {
 38     e[++tot]=(edge){x,y,head[x],z,w};head[x]=tot;
 39     e[++tot]=(edge){y,x,head[y],0,-w};head[y]=tot;
 40 }
 41 bool spfa()
 42 {
 43     for (int i=s;i<=t;i++){v[i]=0;d[i]=inf;}
 44     q.push(s);d[s]=0;v[s]=1;
 45     while(!q.empty())
 46     {
 47         int x=q.front();q.pop();v[x]=0;
 48         for (int i=head[x],y;i;i=e[i].next)
 49          if(e[i].v&&d[x]+e[i].c<d[y=e[i].go])
 50          {
 51             d[y]=d[x]+e[i].c;from[y]=i;
 52             if(!v[y]){v[y]=1;q.push(y);}
 53          }
 54     }
 55     return d[t]!=inf;
 56 }
 57 void mcf()
 58 {
 59     mincost=0;maxflow=0;
 60     while(spfa())
 61     {
 62         int tmp=inf;
 63         for(int i=from[t];i;i=from[e[i].from]) tmp=min(tmp,e[i].v);
 64         mincost+=d[t]*tmp;maxflow+=tmp;
 65         for(int i=from[t];i;i=from[e[i].from]){e[i].v-=tmp;e[i^1].v+=tmp;}
 66     }
 67 }
 68 int main()
 69 {
 70     freopen("input.txt","r",stdin);
 71     freopen("output.txt","w",stdout);
 72     int T=read(),cs=0;
 73     while(T--)
 74     {
 75         n=read();m=read();k=read();sum=0;
 76         s=0;ss=2*n+1;t=ss+1;
 77         memset(head,0,sizeof(head));tot=1;
 78         for1(i,n)
 79         {
 80             a[i]=read();sum+=a[i];
 81             add(s,i,a[i],0);
 82             add(i+n,t,a[i],0);
 83         }
 84         for1(i,n-1)add(i,i+1,inf,0);
 85         for1(i,m)
 86         {
 87             int x=read(),y=read();
 88             add(s,ss,x,y);
 89         }
 90         for1(i,n)add(ss,i+n,inf,0);
 91         for1(i,k)
 92         {
 93             int x=read(),y=read();
 94             for1(j,n-x-1)add(j,j+x+1+n,inf,y);
 95         }
 96         mcf();
 97         printf("Case %d: ",++cs);
 98         if(maxflow!=sum)printf("impossible\n");else printf("%d\n",mincost);
 99     }
100                 
101     return 0;
102 }