最大ストリーム問題プリフロー推進アルゴリズム(BFS最適化)

/*
  Name:            
  Copyright: 
  Author:     
  Date: 14-06-17 09:26
  Description:          ，     ：
         BFS  ，
        ，                .
*/
#include    
#include   
    
using namespace std;   

typedef struct VertexNode{ //     
    int num;  //          
    struct VertexNode *next; //  ，       
} VertexNode;
    
const int MAXV=2000;   //           
const int MAXE=2000;   //         
const int INFINITY = 0x7fffffff;   //        
int capacity[MAXV][MAXV]; //             
int flow[MAXV];  //                
int dis[MAXV]; //           
VertexNode *head; //           
    
int MaxFlow_relabel_to_front(int src, int des, int n) ;    
bool BFS(int src, int des, int n); //               
void Check(int u, int n); //   u             ，        0  
    
int main()    
{   
    int  m, n, u, v;    
    ifstream fcin("maxflow.txt");  
      
    if (!fcin.is_open())  
    {  
        cout << "Error opening file"; exit (1);  
    }  
    
    fcin >> n >> m;  
     
    for(int i=0; i> u >> v;    
        fcin >> capacity[u][v];        
    }    
      
    cout << n << " " << m << endl;  
    for (int i=0; i 0)
    {
        //     u  relabel  
        bool relabel = true;  
        for (int v=0; v 0) //     ，      
		 	{
                relabel = false;  
   	            minFlow = (flow[u] < capacity[u][v]) ? flow[u] : capacity[u][v];	   
                flow[u] -= minFlow;  
				flow[v] += minFlow;  
				capacity[u][v] -= minFlow;  
				capacity[v][u] += minFlow; 
				printf("push %d --%d--> %d, e[%d] = %d
", u, minFlow, v, u, flow[u]);  
				if (flow[u] == 0)
				{
  		            break;
                }
			}
		}
					//    push   ,  relabel  
        if (relabel) 
		{   
            minLevel = INFINITY; 
 	        for (int v=0; v 0 && minLevel > dis[v]) //         
                {
		            minLevel = dis[v];
                } 
            }
            dis[u] = minLevel + 1;
            printf("relabel %d height to %d
", u, dis[u]); 
        }  
    }
}  
    
int MaxFlow_relabel_to_front(int src, int des, int n)    
{           
    int u, v, oldLevel, minFlow; 
	VertexNode *p = head;
      
    if (BFS(src, des, n))//          
    {   
        dis[src] = n;  //          n
	    for (v = 0; v < n; v++) //             
		{  
	        if (capacity[src][v] > 0) //              
			{  
	            flow[src] -= capacity[src][v];  
	            flow[v] = capacity[src][v];  
	            capacity[v][src] = capacity[src][v];  
	            capacity[src][v] = 0; 
	        }  
	    }   
	    
	    VertexNode *pre = head;   
	    while (pre->next)
	    {
	 	    u = pre->next->num;
		 	oldLevel = dis[u];
		 	Check(u, n);
		 	
		 	if (oldLevel < dis[u])//     ，       
			{
	 	        p = pre->next;
	 	        pre->next = p->next; //    p 
	 	        p->next = head->next;//   p         
	 	        head->next = p;
	 	        pre = head;
			} 
			
			pre = pre->next; //       
		} 
    }
    
    p = head->next;
    while (p)
    {
	     delete head;
	     head = p;
	     p = head->next;
    }
    
    return flow[des];    
}    

bool BFS(int src, int des, int n)//              ，       ，   false    
{    
    int Queue[MAXV];   //                  
    int v, front = 0, rear = 0; //         
        
    for(int i=0; inext = NULL;
    for (front = 1; front < rear; front++)//                  
    {
	 	if (Queue[front] != src)
	 	{ 				 
		 	s = new VertexNode;
		 	s->num = Queue[front];  
		 	s->next = head->next;
		 	head->next = s;
		}
	}
        
    return true; 
}