World Exhibition hdu 3592 差分约束

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <vector>
#include <deque>

using namespace std;

const int inf = 0x7f7f7f7f;

struct node 
{
    int x, v;
    
}Nd;

int N1,M1,P1,f1;
vector<node>T[11010];
deque<int>q;



bool flag[11010] = {false};
int dis[11020];
int hash[11020];


void debug( )
{
    #ifdef P
    freopen("in.txt","r",stdin);
    freopen("out.txt","w",stdout);
    #endif
}

int spfa(  )
{
    int t;
    vector<node>::iterator iter;
    q.push_back(1);
    dis[1] = 0;
    flag[1] = 1;
    while ( !q.empty( ) )
    {
        t =  q.front( );
        flag[t] = 0;
        q.pop_front( );
        for ( iter = T[t].begin( ); iter != T[t].end( ); iter++) {
            if ( dis[iter->x] > dis[t] + iter->v ) {
                dis[iter->x] = dis[t] + iter->v;
                if ( !flag[iter->x] )
                {   
                    flag[iter->x] = 1;
                    q.push_back(iter->x);
                
                }
                if ( ++hash[iter->x] > P1)
                  {
                    return -1;
                  }
                    
            }
        }
    }
    if (dis[P1] == inf)
        return -2;
    return dis[P1];
}
            
            
void init(   )
{
    int i;
    q.clear();
    for (i = 0; i <= 1000; i++) 
        T[i].clear(), flag[i] = 0;
    memset(dis, 0, sizeof(dis));
    memset(hash, 0, sizeof(hash));
    for ( i = 1; i <= 1000; i++) {
        dis[i] = inf;
    }

}

void print( int x)
{
    int i;
    for (i = 0; i <= x; i++)
        printf("%d ",dis[i]);
    puts("");
}
         
int main( )
{
    int  i, j, a, b, c, d, t;
    debug( );
    scanf("%d",&t);
    while (t--)
     {
        scanf("%d%d%d",&P1,&N1,&M1);   
        init( );
        /*
        for (i = 2; i <= P1; i++)
           {
                Nd.x = i -1 ;
                Nd.v = 0;
                T[i].push_back(Nd);
            }
            *///不加也能A 
        for (i = 1; i <= N1; i++) {
             scanf("%d%d%d", &a, &b, &d); // xb - xa <= d        insert(a, b, d)
             Nd.x = b, Nd.v = d;       
             T[a].push_back(Nd);
        }     
        for (i = 1; i <= M1; i++) {
            scanf("%d%d%d",&a, &b, &c); // xb- xa >= d   xa- xb <= -d   insert(b, a, -d)
            Nd.x = a, Nd.v = -c;
            T[b].push_back(Nd);
        }
    
        printf("%d\n",spfa( ));
        
        //print(N);
    }
    return 0;
}
/* 
 题目要求的是求 最大值。即最短路 <= 
 d[j] < d[i] + map[i][j];
 d[j] - d[i] < map[i][j]
  xb - xa <= d
  insert(i, j, d);
  xb - xa >= d
  xa - xb <= -d
  最小值最长路 >=
  d[j] > d[i] + map[i][j];
  d[j] - d[i] > map[i][j]
  insert(i, j, d); 
  差分约束系统(SPFA)  
对于差分约束系统，建立的不等式是>=则在SPFA中求最长路。A-B>=C，则从B连一条权为C的边到A。
反之求最短路。A-B<=C，则从B连一条权为C的边到A。
注意两者对DIS初始化的不同
*/
   

World Exhibition