HDU 4975 A simple Gaussian elimination problem.

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <cstring>
  4 #include <queue>
  5 using namespace std;
  6 const int maxn = 1010;
  7 const int INF = 0x3f3f3f3f;
  8 struct arc{
  9     int to,flow,next;
 10     arc(int x = 0,int y = 0,int z = -1){
 11         to = x;
 12         flow = y;
 13         next = z;
 14     }
 15 }e[1000000];
 16 int head[maxn],d[maxn],cur[maxn],tot,S,T;
 17 bool vis[maxn],hv[maxn];
 18 void add(int u,int v,int flow){
 19     e[tot] = arc(v,flow,head[u]);
 20     head[u] = tot++;
 21     e[tot] = arc(u,0,head[v]);
 22     head[v] = tot++;
 23 }
 24 bool bfs(){
 25     queue<int>q;
 26     memset(d,-1,sizeof d);
 27     d[S] = 1;
 28     q.push(S);
 29     while(!q.empty()){
 30         int u = q.front();
 31         q.pop();
 32         for(int i = head[u]; ~i; i = e[i].next){
 33             if(e[i].flow && d[e[i].to] == -1){
 34                 d[e[i].to] = d[u] + 1;
 35                 q.push(e[i].to);
 36             }
 37         }
 38     }
 39     return d[T] > -1;
 40 }
 41 int dfs(int u,int low){
 42     if(u == T) return low;
 43     int tmp = 0,a;
 44     for(int &i = cur[u]; ~i; i = e[i].next){
 45         if(e[i].flow && d[e[i].to] == d[u]+1&&(a=dfs(e[i].to,min(low,e[i].flow)))){
 46             e[i].flow -= a;
 47             e[i^1].flow += a;
 48             low -= a;
 49             tmp += a;
 50             if(!low) break;
 51         }
 52     }
 53     if(!tmp) d[u] = -1;
 54     return tmp;
 55 }
 56 int dinic(){
 57     int ret = 0;
 58     while(bfs()){
 59         memcpy(cur,head,sizeof head);
 60         ret += dfs(S,INF);
 61     }
 62     return ret;
 63 }
 64 bool dfs2(int u,int fa){
 65     if(vis[u]) return true;
 66     vis[u] = true;
 67     for(int i = head[u]; ~i; i = e[i].next)
 68         if(!hv[e[i].to] && e[i].flow && e[i].to != fa && dfs2(e[i].to,u)) return true;
 69     hv[u] = true;
 70     return vis[u] = false;
 71 }
 72 int main(){
 73     int Ts,n,m,tmp,sum,sum2,cs = 1;
 74     scanf("%d",&Ts);
 75     while(Ts--){
 76         scanf("%d %d",&n,&m);
 77         memset(head,-1,sizeof head);
 78         memset(hv,false,sizeof hv);
 79         sum2 = sum = S = tot = 0;
 80         T = n + m + 1;
 81         for(int i = 1; i <= n; ++i){
 82             scanf("%d",&tmp);
 83             add(S,i,tmp);
 84             sum += tmp;
 85             for(int j = 1; j <= m; ++j)
 86                 add(i,j+n,9);
 87         }
 88         for(int i = 1; i <= m; ++i){
 89             scanf("%d",&tmp);
 90             add(i+n,T,tmp);
 91             sum2 += tmp;
 92         }
 93         if(sum == sum2){
 94             if(sum == dinic()){
 95                 bool flag = false;
 96                 memset(vis,false,sizeof vis);
 97                 for(int i = 1; i <= n; ++i)
 98                     if(flag = dfs2(i,-1)) break;
 99                 if(flag) printf("Case #%d: So young!\n",cs++);
100                 else printf("Case #%d: So simple!\n",cs++);
101             }else printf("Case #%d: So naive!\n",cs++);
102         }else printf("Case #%d: So naive!\n",cs++);
103     }
104     return 0;
105 }