HDU-3339 最短路+背包问题

/*
* hdu-3339
* mike-w
* 2012-4-14
*/
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define MAX_SIZE 128
#define Q_SIZE 256
#define TOTAL_DIST_MAX (MAX_SIZE*MAX_SIZE-100)
#define INF 99999999
#define min(a,b) ((a)<(b)?(a):(b))
#define max(a,b) ((a)<(b)?(b):(a))

int p[MAX_SIZE];
int f[MAX_SIZE][MAX_SIZE];
int dst[MAX_SIZE];
int opt[MAX_SIZE*MAX_SIZE];
int que[Q_SIZE],qhead,qtail,qlen;
int inq[MAX_SIZE];
int T,N,M;

int enque(int e)
{
if(qlen==Q_SIZE)
return -1;
qlen++;
que[qtail]=e;
qtail=(qtail+1)%Q_SIZE;
return 0;
}

int deque(int *e)
{
if(qlen==0)
return -1;
qlen--;
*e=que[qhead];
qhead=(qhead+1)%Q_SIZE;
return 0;
}

int spfa(void)
{
int i,x;
qhead=qtail=qlen=0;
for(i=0;i<=N;i++)
dst[i]=INF,inq[i]=0;
dst[0]=0;
enque(0);
inq[0]=1;
while(deque(&x)!=-1)
{
inq[x]=0;
for(i=0;i<=N;i++)
if(dst[x]+f[x][i]<dst[i])
{
dst[i]=dst[x]+f[x][i];
if(!inq[i])
enque(i),inq[i]=1;
}
}
return 0;
}

int main(void)
{
#ifndef ONLINE_JUDGE
freopen("in","r",stdin);
#endif
int i,j,t1,t2,t3;
int min_cost;
int half_power,total_power;
scanf("%d",&T);
while(T-->0)
{
scanf("%d%d",&N,&M);
/* initialize */
for(i=0;i<=N;i++)
for(j=0;j<=N;j++)
f[i][j]=INF;
memset(p,0,sizeof(p));
/* read input */
for(i=1;i<=M;i++)
{
scanf("%d%d%d",&t1,&t2,&t3);
f[t1][t2]=f[t2][t1]=min(f[t1][t2],t3);
}
total_power=half_power=0;
for(i=1;i<=N;i++)
scanf("%d",p+i),total_power+=p[i];
half_power=total_power/2;
/* calculate shortest path */
spfa();
/* backpack problem */
memset(opt,0,sizeof(opt));
for(i=1;i<=N;i++)
for(j=TOTAL_DIST_MAX;j>=dst[i];j--)
opt[j]=max(opt[j],opt[j-dst[i]]+p[i]);
min_cost=INF;
for(i=0;i<=TOTAL_DIST_MAX;i++)
if(opt[i]>half_power)
min_cost=i,i=TOTAL_DIST_MAX+1;
if(min_cost==INF)
puts("impossible");
else
printf("%d\n",min_cost);
}
return 0;
}