Codeforces 546E Soldier and Traveling（最大流）

  1 #include<cstdio>
  2 #include<cstring>
  3 #include<queue>
  4 #include<algorithm>
  5 using namespace std;
  6 #define INF (1<<30)
  7 #define MAXN 222
  8 #define MAXM 222*222*2
  9 
 10 struct Edge{
 11     int v,cap,flow,next;
 12 }edge[MAXM];
 13 int vs,vt,NE,NV;
 14 int head[MAXN];
 15 
 16 void addEdge(int u,int v,int cap){
 17     edge[NE].v=v; edge[NE].cap=cap; edge[NE].flow=0;
 18     edge[NE].next=head[u]; head[u]=NE++;
 19     edge[NE].v=u; edge[NE].cap=0; edge[NE].flow=0;
 20     edge[NE].next=head[v]; head[v]=NE++;
 21 }
 22 
 23 int level[MAXN];
 24 int gap[MAXN];
 25 void bfs(){
 26     memset(level,-1,sizeof(level));
 27     memset(gap,0,sizeof(gap));
 28     level[vt]=0;
 29     gap[level[vt]]++;
 30     queue<int> que;
 31     que.push(vt);
 32     while(!que.empty()){
 33         int u=que.front(); que.pop();
 34         for(int i=head[u]; i!=-1; i=edge[i].next){
 35             int v=edge[i].v;
 36             if(level[v]!=-1) continue;
 37             level[v]=level[u]+1;
 38             gap[level[v]]++;
 39             que.push(v);
 40         }
 41     }
 42 }
 43 
 44 int pre[MAXN];
 45 int cur[MAXN];
 46 int ISAP(){
 47     bfs();
 48     memset(pre,-1,sizeof(pre));
 49     memcpy(cur,head,sizeof(head));
 50     int u=pre[vs]=vs,flow=0,aug=INF;
 51     gap[0]=NV;
 52     while(level[vs]<NV){
 53         bool flag=false;
 54         for(int &i=cur[u]; i!=-1; i=edge[i].next){
 55             int v=edge[i].v;
 56             if(edge[i].cap!=edge[i].flow && level[u]==level[v]+1){
 57                 flag=true;
 58                 pre[v]=u;
 59                 u=v;
 60                 //aug=(aug==-1?edge[i].cap:min(aug,edge[i].cap));
 61                 aug=min(aug,edge[i].cap-edge[i].flow);
 62                 if(v==vt){
 63                     flow+=aug;
 64                     for(u=pre[v]; v!=vs; v=u,u=pre[u]){
 65                         edge[cur[u]].flow+=aug;
 66                         edge[cur[u]^1].flow-=aug;
 67                     }
 68                     //aug=-1;
 69                     aug=INF;
 70                 }
 71                 break;
 72             }
 73         }
 74         if(flag) continue;
 75         int minlevel=NV;
 76         for(int i=head[u]; i!=-1; i=edge[i].next){
 77             int v=edge[i].v;
 78             if(edge[i].cap!=edge[i].flow && level[v]<minlevel){
 79                 minlevel=level[v];
 80                 cur[u]=i;
 81             }
 82         }
 83         if(--gap[level[u]]==0) break;
 84         level[u]=minlevel+1;
 85         gap[level[u]]++;
 86         u=pre[u];
 87     }
 88     return flow;
 89 }
 90 
 91 int ans[111][111];
 92 int main(){
 93     int n,m;
 94     scanf("%d%d",&n,&m);
 95     vs=0; vt=2*n+1; NV=vt+1; NE=0;
 96     memset(head,-1,sizeof(head));
 97     int a,b;
 98     int tot1=0,tot2=0;
 99     for(int i=1; i<=n; ++i){
100         scanf("%d",&a);
101         addEdge(vs,i,a);
102         tot1+=a;
103     }
104     for(int i=1; i<=n; ++i){
105         scanf("%d",&a);
106         addEdge(i+n,vt,a);
107         tot2+=a;
108     }
109     int tag=NE;
110     for(int i=1; i<=n; ++i){
111         addEdge(i,i+n,INF);
112     }
113     while(m--){
114         scanf("%d%d",&a,&b);
115         addEdge(a,b+n,INF);
116         addEdge(b,a+n,INF);
117     }
118     if(tot1==tot2 && ISAP()==tot2){
119         puts("YES");
120         for(int i=tag; i<NE; i+=2){
121             int u=edge[i^1].v,v=edge[i].v-n;
122             ans[u][v]=edge[i].flow;
123         }
124         for(int i=1; i<=n; ++i){
125             for(int j=1; j<=n; ++j){
126                 printf("%d ",ans[i][j]);
127             }
128             putchar(‘\n‘);
129         }
130     }else{
131         puts("NO");
132     }
133     return 0;
134 }