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：

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 typedef unsigned int ui;
 4 typedef long long ll;
 5 typedef unsigned long long ull;
 6 #define pf printf
 7 #define mem(a,b) memset(a,b,sizeof(a))
 8 #define prime1 1e9+7
 9 #define prime2 1e9+9
10 #define pi 3.14159265
11 #define lson l,mid,rt<<1
12 #define rson mid+1,r,rt<<1|1
13 #define scand(x) scanf("%llf",&x) 
14 #define f(i,a,b) for(int i=a;i<=b;i++)
15 #define scan(a) scanf("%d",&a)
16 #define mp(a,b) make_pair((a),(b))
17 #define P pair<int,int>
18 #define dbg(args) cout<<#args<<":"<<args<<endl;
19 #define inf 0x3f3f3f3f
20 const int maxn=1e4+5;
21 int n,m,t,e;
22 int c[maxn],head[maxn],nxt[maxn],pre[maxn],d[maxn],in[maxn];
23 void init()
24 {
25     e=0;
26     mem(head,-1);
27     mem(nxt,-1);
28     mem(pre,0); 
29     mem(d,-inf);
30     mem(in,0);
31 }
32 struct edge{
33     int v,w;
34 }p[maxn];
35 void addedge(int u,int v,int w)
36 {
37     p[e].v=v;
38     p[e].w=w;
39     nxt[e]=head[u];
40     head[u]=e++;
41 }
42 void SPFA(int src)
43 {
44     d[src]=0;
45     queue<int>q;
46     q.push(src);
47     in[src]=1;
48     while(!q.empty())
49     {
50         int now=q.front();
51         q.pop();
52         in[now]=0;
53         for(int i=head[now];~i;i=nxt[i])
54         {
55             if(d[p[i].v]<d[now]+p[i].w)
56             {
57                 pre[p[i].v]=now;
58                 d[p[i].v]=d[now]+p[i].w;
59                 in[p[i].v]=1;
60                 q.push(p[i].v);
61             }
62         }
63     }
64 }
65 void print(int now)
66 {
67     if(pre[now]==0)return;
68     print(pre[now]);
69     pf("->%d",now);
70 }
71 int main()
72 {
73     //freopen("input.txt","r",stdin);
74     //freopen("output.txt","w",stdout);
75     std::ios::sync_with_stdio(false);
76     scan(t);
77     f(tt,1,t) 
78     {
79         init();
80         scan(n);
81         f(i,1,n)scan(c[i]);
82         scan(m);
83         int u,v;
84         f(i,1,m)
85         {
86             scanf("%d%d",&u,&v);
87             if(v==n+1)addedge(u,v,0);
88             else addedge(u,v,c[v]);
89         }
90         SPFA(1);
91         pf("CASE %d#\n",tt);
92         pf("points : %d\n",d[n+1]);
93         pf("circuit : 1");
94         print(pre[n+1]);
95         pf("->1\n");
96         if(tt!=t)pf("\n");
97     }
98  }