最大流模板 ISAP

邻接矩阵：

 1 #include<stdio.h>

 2 #include<string.h>

 3 #include<stdlib.h>

 4 #define MIN(a,b) (a)<(b)?(a):(b)

 5 const int M = 110;

 6 const int inf = 0x3fffffff;

 7 int n, m, A[1010], pre[1010];

 8 int remain[M][M], h[M], vh[M], S, T, N;39 int DFS( int u, int flow ) 

40 {

41     if( u == T ) return flow;//找到增广路

42     int tmp = h[u]+1, sum = flow; //更新当前点层数

43     for(int v = 0; v < N; v++)

44     {

45         if( remain[u][v] && h[u] == h[v]+1 ) //允许弧,且一层差别

46         {

47             int p = DFS( v, MIN( sum, remain[u][v]) );

48             remain[u][v] -= p; remain[v][u] += p; sum -= p; //更新残留网络

49             if( sum == 0 || h[S] == N ) return flow-sum;    

50         }

51     }

52     for(int v = 0; v < N; v++)

53         if( remain[u][v] )    

54             tmp = MIN( tmp, h[v] );

55     if( !( --vh[ h[u] ] ) ) h[S] = N; //间隙优化,当出现断层即可判定无增广路

56     else    ++vh[ h[u] = tmp+1 ]; 

57     return flow-sum;

58 }

59 void sap()

60 {

61     int maxflow = 0;

62     memset( h, 0, sizeof(h));

63     memset( vh, 0, sizeof(vh));

64     vh[S] = N; //0层节点数量为N

65     while( h[S] < N )    maxflow += DFS( S, inf );

66     printf("%d\n", maxflow );

67 }

 

静态链表：

 1 #include<cstdio>

 2 #include<cstdlib>

 3 #include<cstring>

 4 #include<string>

 5 #include<algorithm>

 6 #include<vector>

 7 using namespace std;

 8 

 9 const int inf = 0x3f3f3f3f;

10 int n, m, K;

11 int N, M, S, T;

12 bool mp[100][100];

13 int vh[500], h[500];

14 

15 struct node{

16     int v, f, nxt;

17 }edge[250000];

18 int head[500], idx;

19 

20 void addedge(int u,int v,int f){

21     edge[idx].v = v; edge[idx].f = f;

22     edge[idx].nxt = head[u]; head[u] = idx++;

23     

24     edge[idx].v = u; edge[idx].f = 0;

25     edge[idx].nxt = head[v]; head[v] = idx++;

26 }

27 void CreateGraph(int L){

28     idx = 0;

29     memset(head,-1,sizeof(head));

30 

31     for(int x = 1; x <= n; x++){

32         addedge( S, x, L );

33         for(int y = 1; y <= m; y++){

34             if( mp[x][y] ) addedge(x,n+y,1);

35             else addedge(x,m+n+y,1); 

36         }

37     }

38     for(int y = 1; y <= m; y++){

39         addedge( n+y, n+2*m+y , n );

40         addedge( n+m+y, n+2*m+y, K );

41         addedge( n+2*m+y, T, L );

42     }    

43 }

44 int dfs(int u,int flow){

45     if( u == T ) return flow;

46     int tmp = h[u]+1, sum = flow;

47     for(int i = head[u]; ~i; i = edge[i].nxt ){

48         if( edge[i].f && (h[edge[i].v]+1==h[u]) ){

49             int p = dfs( edge[i].v , min(sum,edge[i].f) );    

50             edge[i].f -= p; edge[i^1].f += p; sum -= p;

51             if( sum == 0 || h[S] == N ) return flow-sum;

52         }    

53     }

54     for(int i = head[u]; ~i; i = edge[i].nxt )        

55         if( edge[i].f ) tmp = min( tmp, h[ edge[i].v ] );

56     if( --vh[ h[u] ] == 0 ) h[S] = N;

57     else ++vh[ h[u]=tmp+1 ];

58     return flow-sum;

59 }

60 int SAP(){

61     int maxflow = 0;

62     memset(vh,0,sizeof(vh));

63     memset(h,0,sizeof(h));

64     vh[S] = N;

65     while( h[S] < N ) maxflow += dfs( S, inf );

66     return maxflow;

67 }