uva820 最大流模板题

来源：互联网发布：社交网络免费观看编辑：程序博客网时间：2024/06/03 15:38

注意以下输出格式，还有就是有重边。

这是邻接表的做法：

#include<iostream>#include<cstring>#include<cstdlib>#include<cstdio>#include<cmath>#include<string>#include<map>#include<set>#include<algorithm>#include<vector>#include<stack>#include<queue>#include<sstream>#define LL long long#define OJ_PRINT 0#define READ_FILE 0using namespace std;const int NN_MAX = 110;const int MM_MAX = NN_MAX*NN_MAX;const int INF = 0x1fffffff;struct Edge{  int from,to,cap,flow;  Edge (int a1,int a2,int a3,int a4):from (a1),to (a2),cap (a3),flow (a4){}  Edge (){}}theEdge[MM_MAX*4];/**********************************************************/int n,m,s,t;vector<int>G[NN_MAX];int a[NN_MAX],p[NN_MAX];int flow=0;/**********************************************************/int min_2 (int x,int y) {return x<y?x:y;}int max_2 (int x,int y) {return x>y?x:y;}void EK ();/**********************************************************/int main(){  if (READ_FILE) freopen ("in.txt","r",stdin);  int tt=1;  while (scanf ("%d",&n) && n)  {scanf ("%d %d %d",&s,&t,&m);for (int i=0;i<=n;i++)  G[i].clear ();int a1,a2,a3;int lenEdge=0;for (int i=0;i<m;i++){  scanf ("%d%d%d",&a1,&a2,&a3);  theEdge[lenEdge++]=Edge (a1,a2,a3,0); G[a1].push_back (lenEdge-1);  theEdge[lenEdge++]=Edge (a2,a1,0,0); G[a2].push_back (lenEdge-1);  theEdge[lenEdge++]=Edge (a2,a1,a3,0); G[a2].push_back (lenEdge-1);  theEdge[lenEdge++]=Edge (a1,a2,0,0); G[a1].push_back (lenEdge-1);}flow=0;EK ();//if (tt>1) printf ("\n");printf ("Network %d\nThe bandwidth is %d.\n\n",tt++,flow);  }  return 0;}void EK (){  while (1)  {memset (a,0,sizeof (a));queue<int>qee; qee.push (s);a[s]=INF;while (!qee.empty ()){  int x=qee.front (); qee.pop ();  for (int i=0;i<G[x].size ();i++){Edge& e=theEdge[G[x][i]];if (!a[e.to] && e.cap>e.flow){  p[e.to]=G[x][i];  a[e.to]=min_2 (a[x],e.cap-e.flow);  qee.push (e.to);}  }  //if (a[t]) break;}if (a[t]==0) break;flow+=a[t];for (int i=t;i!=s;i=theEdge[p[i]].from){  theEdge[p[i]].flow+=a[t];  theEdge[p[i]^1].flow-=a[t];}  }}

这是邻接矩阵的做法：

#include<iostream>#include<cstring>#include<cstdlib>#include<cstdio>#include<cmath>#include<string>#include<map>#include<set>#include<algorithm>#include<vector>#include<stack>#include<queue>#include<sstream>#define LL long long#define OJ_PRINT 0#define READ_FILE 0using namespace std;const int NN_MAX = 110;const int INF = 0x1fffffff;/**********************************************************/int n,m,s,t;int a[NN_MAX],p[NN_MAX],cap[NN_MAX][NN_MAX],flow[NN_MAX][NN_MAX];int maxflow=0;/**********************************************************/int min_2 (int x,int y) {return x<y?x:y;}int max_2 (int x,int y) {return x>y?x:y;}void EK ();/**********************************************************/int main(){  if (READ_FILE) freopen ("in.txt","r",stdin);  int tt=1;  while (scanf ("%d",&n) && n)  {scanf ("%d %d %d",&s,&t,&m);int a1,a2,a3;int lenEdge=0;memset (cap,0,sizeof (cap));memset (flow,0,sizeof (flow));for (int i=0;i<m;i++){  scanf ("%d%d%d",&a1,&a2,&a3);  cap[a1][a2]+=a3;  cap[a2][a1]=cap[a1][a2];}maxflow=0;EK ();printf ("Network %d\nThe bandwidth is %d.\n\n",tt++,maxflow);  }  return 0;}void EK (){  while (1)  {queue<int>qee;memset (a,0,sizeof (a)); a[s]=INF;qee.push (s);while (!qee.empty ()){  int x=qee.front (); qee.pop ();  for (int y=1;y<=n;y++){if (!a[y] && cap[x][y]>flow[x][y]){  a[y]=min_2 (a[x],cap[x][y]-flow[x][y]);  p[y]=x;  qee.push (y);}  }}if (a[t]==0) break;maxflow+=a[t];for (int i=t;i!=s;i=p[i]){  flow[p[i]][i]+=a[t];  flow[i][p[i]]-=a[t];}  }}

0 0