POJ 1459 ZOJ 1734 Power Network dinic 算法 网络流
裸的网络流，就是在读数据的时候，注意用while(getchar()!='(');scanf("%d,%d),%d");
然后增加超源点与超收点。我是用dinic算法，速度慢，跑了549貌似ms，貌似，希望能优化，用个什么预流推进算法试试啊。
在纠结了很久后，终于在书上把预流推进算法抄下来了，哈哈，调试了很久，一直陷入死循环，后来一看输入文件不是这个题的输入，想shi啊，有木有
贴代码 dinic 算法 ：
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1 #include <cstdio> 2 #include <cstring> 3 #define MAXN 108 4 #define INF 300000000 5 int n,np,nc,m; 6 int s ;//源点 7 int t; //汇点 8 int map[MAXN][MAXN];//容量网络 9 bool sign[MAXN][MAXN];//层次网络 10 void init() 11 { 12 int i; 13 int u,v,z; 14 s = n; 15 t = n+1; 16 memset(map,0,sizeof(map)); 17 for(i=0; i<m; ++i) 18 { 19 while(getchar() != '('); 20 scanf("%d,%d)%d",&u,&v,&z); 21 map[u][v] = z; 22 } 23 for(i=0; i<np; ++i) 24 { 25 while(getchar() != '('); 26 scanf("%d)%d",&u,&z); 27 map[s][u] = z; 28 } 29 for(i =0; i<nc; ++i) 30 { 31 while(getchar() != '('); 32 scanf("%d)%d",&u,&z); 33 map[u][t] = z; 34 } 35 } 36 int min(int x,int y) 37 { 38 return x<y ? x : y; 39 } 40 bool BFS() 41 { 42 bool used[MAXN]; 43 int queue[MAXN]; 44 int fr=0,ta=0; 45 int i; 46 memset(used,0,sizeof(used)); 47 memset(sign,0,sizeof(sign)); 48 queue[ta++] = s; 49 used[s] = 1; 50 while(fr != ta) 51 { 52 int v = queue[fr++]; 53 for(i=0; i<=n+1; ++i) 54 { 55 if(!used[i] && map[v][i]) 56 { 57 queue[ta++] = i; 58 sign[v][i] = 1; 59 used[i] = 1; 60 } 61 } 62 } 63 return used[t]; 64 } 65 int DFS(int v,int sum) 66 { 67 int i,r,f; 68 if(v == t) return sum; 69 r = sum; 70 for(i=0; i<=n+1; ++i) 71 { 72 if(sign[v][i]) 73 { 74 f=DFS(i,min(map[v][i],sum)); 75 map[v][i] -=f; 76 map[i][v] += f; 77 sum -= f; 78 } 79 } 80 return r-sum; 81 } 82 int main() 83 { 84 // freopen("in.cpp","r",stdin); 85 while(~scanf("%d%d%d%d",&n,&np,&nc,&m)) 86 { 87 init(); 88 int ans = 0; 89 while(BFS()) ans += DFS(s,INF); 90 printf("%d\n",ans); 91 } 92 return 0; 93 }
预流推进算法，只跑了150ms,貌似：
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1 #include <cstdio> 2 #include <cstring> 3 #include <queue> 4 #define MAXN 110 5 #define INF 0x7fffffff //相当于21，4748，3647 6 using namespace std; 7 int s,t; //源点和汇点 8 queue<int> act; 9 int h[MAXN]; //高度 10 int ef[MAXN]; //余流，能流出去多少 11 int n,np,nc,m; 12 int resi[MAXN][MAXN];//残留网络，每条边的权值表示容量 13 int min(int x,int y) 14 { 15 if(x <y)return x; 16 else return y; 17 } 18 void pushRelabel() 19 { 20 int i; 21 int sum=0; 22 int u,p; 23 memset(ef,0,sizeof(ef)); 24 memset(h,0,sizeof(h)); 25 h[s] = n+2; 26 ef[s] = INF;//源点能往外流正无穷 27 ef[t] = -INF;//汇点不能往外流，所以汇点能往外流负无穷 28 act.push(s); 29 while(!act.empty()) 30 { 31 u = act.front(); 32 act.pop(); 33 for(i=0; i<=n+1; ++i) 34 { 35 p = min(resi[u][i],ef[u]); 36 if(p > 0 && (u==s || h[u] == h[i]+1)) 37 { 38 resi[u][i] -= p; 39 resi[i][u] += p; 40 ef[u] -= p; 41 ef[i] += p; 42 if(i == t) sum += p; 43 if(i != s && i!=t) 44 act.push(i); 45 } 46 } 47 if(u != s && u != t && ef[u] > 0) 48 { 49 h[u]++; 50 act.push(u); 51 } 52 } 53 printf("%d\n",sum); 54 } 55 int main() 56 { 57 // freopen("in.cpp","r",stdin); 58 int i; 59 int u,v,val; 60 while(~scanf("%d%d%d%d",&n,&np,&nc,&m)) 61 { 62 s = n; 63 t = n+1; 64 memset(resi,0,sizeof(resi)); 65 for(i=0; i<m; ++i) 66 { 67 while(getchar()!='('); 68 scanf("%d,%d)%d",&u,&v,&val); 69 resi[u][v] = val; 70 } 71 for(i=0; i<np; ++i) 72 { 73 while(getchar()!='('); 74 scanf("%d)%d",&u,&val); 75 resi[s][u] = val; 76 } 77 for(i=0; i<nc; ++i) 78 { 79 while(getchar()!='('); 80 scanf("%d)%d",&u,&val); 81 resi[u][t] = val; 82 } 83 pushRelabel(); 84 } 85 return 0; 86 }
