hdu1224SPFA求最长路加上打印路径

题目链接：http://icpc.njust.edu.cn/Problem/Hdu/1224/

无负环。

代码如下：

 #include<bits/stdc++.h>
 using namespace std;
 typedef unsigned int ui;
 typedef long long ll;
 typedef unsigned long long ull;
 #define pf printf
 #define mem(a,b) memset(a,b,sizeof(a))
 #define prime1 1e9+7
 #define prime2 1e9+9
 #define pi 3.14159265
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define scand(x) scanf("%llf",&x)
 #define f(i,a,b) for(int i=a;i<=b;i++)
 #define scan(a) scanf("%d",&a)
 #define mp(a,b) make_pair((a),(b))
 #define P pair<int,int>
 #define dbg(args) cout<<#args<<":"<<args<<endl;
 #define inf 0x3f3f3f3f
 const int maxn=1e4+;
 int n,m,t,e;
 int c[maxn],head[maxn],nxt[maxn],pre[maxn],d[maxn],in[maxn];
 void init()
 {
     e=;
     mem(head,-);
     mem(nxt,-);
     mem(pre,);
     mem(d,-inf);
     mem(in,);
 }
 struct edge{
     int v,w;
 }p[maxn];
 void addedge(int u,int v,int w)
 {
     p[e].v=v;
     p[e].w=w;
     nxt[e]=head[u];
     head[u]=e++;
 }
 void SPFA(int src)
 {
     d[src]=;
     queue<int>q;
     q.push(src);
     in[src]=;
     while(!q.empty())
     {
         int now=q.front();
         q.pop();
         in[now]=;
         for(int i=head[now];~i;i=nxt[i])
         {
             if(d[p[i].v]<d[now]+p[i].w)
             {
                 pre[p[i].v]=now;
                 d[p[i].v]=d[now]+p[i].w;
                 in[p[i].v]=;
                 q.push(p[i].v);
             }
         }
     }
 }
 void print(int now)
 {
     if(pre[now]==)return;
     print(pre[now]);
     pf("->%d",now);
 }
 int main()
 {
     //freopen("input.txt","r",stdin);
     //freopen("output.txt","w",stdout);
     std::ios::sync_with_stdio(false);
     scan(t);
     f(tt,,t)
     {
         init();
         scan(n);
         f(i,,n)scan(c[i]);
         scan(m);
         int u,v;
         f(i,,m)
         {
             scanf("%d%d",&u,&v);
             if(v==n+)addedge(u,v,);
             else addedge(u,v,c[v]);
         }
         SPFA();
         pf("CASE %d#\n",tt);
         pf("points : %d\n",d[n+]);
         pf("circuit : 1");
         print(pre[n+]);
         pf("->1\n");
         if(tt!=t)pf("\n");
     }
  }