ZQUOJ 1398 Hamilton路径（DFS，稀疏图，n≤40）

 1 #include<bits/stdc++.h>
 2 #define numm ch-48
 3 #define pd putchar(‘ ‘)
 4 #define pn putchar(‘\n‘)
 5 #define pb push_back
 6 #define fi first
 7 #define se second
 8 #define fre1 freopen("1.txt","r",stdin)
 9 #define fre2 freopen("3.txt","w",stdout)
10 #define bug cout<<"*******************"<<endl;
11 #define debug(args...) cout<<#args<<"->"<<args<<"\n";
12 using namespace std;
13 template <typename T>
14 void read(T &res) {
15     bool flag=false;char ch;
16     while(!isdigit(ch=getchar())) (ch==‘-‘)&&(flag=true);
17     for(res=numm;isdigit(ch=getchar());res=(res<<1)+(res<<3)+numm);
18     flag&&(res=-res);
19 }
20 template <typename T>
21 void write(T x) {
22     if(x<0) putchar(‘-‘),x=-x;
23     if(x>9) write(x/10);
24     putchar(x%10+‘0‘);
25 }
26 typedef long long ll;
27 typedef unsigned long long ull;
28 const int maxn=45;
29 const int maxm=205;
30 const int mod=1e9+7;
31 const int inv2=500000004;
32 const int inf=0x3f3f3f3f;
33 const ll INF=0x3f3f3f3f3f3f3f3f;
34 const int N=32;
35 int a[maxn][maxn];
36 vector<int>v;
37 int ans[maxn],minans=inf,n,m,head[maxn],cnt=0;
38 bool flag,vis[maxn];
39 struct node {
40     int v,net,w;
41 }e[maxm];
42 void addedge(int u,int v,int w) {
43     e[++cnt]=(node){v,head[u],w};
44     head[u]=cnt;
45 }
46 void dfs(int st,int step,int now) {
47     if(now>=minans) return ;
48     if(step==n&&st==n) {
49         minans=now;
50         flag=true;
51         for(int i=0;i<v.size();i++)
52             ans[i]=v[i];
53         return ;
54     }
55     for(int i=head[st];~i;i=e[i].net) {
56         int to=e[i].v;
57         if(!vis[to]) {
58             vis[to]=true;
59             v.pb(to);
60             dfs(to,step+1,now+a[st][to]);
61             vis[to]=false;
62             v.pop_back();
63         }
64     }
65 }
66 int main()
67 {
68 //    #define local
69     #ifdef local
70         fre1;
71         fre2;
72     #endif // local
73     read(n),read(m);
74     for(int i=1;i<=n;i++) {
75         head[i]=-1;
76         for(int j=1;j<=n;j++)
77             a[i][j]=inf;
78     }
79     for(int i=1;i<=m;i++) {
80         int u,v,w;
81         read(u),read(v),read(w);
82         a[u][v]=a[u][v]<=w?a[u][v]:w;
83     }
84     for(int i=1;i<=n;i++)
85         for(int j=1;j<=n;j++)
86             if(i!=j&&a[i][j]!=inf)
87                 addedge(i,j,a[i][j]);
88     vis[1]=true;
89     dfs(1,1,0);
90     if(!flag) puts("No solution");
91     else {
92         write(minans);pn;
93         write(1);
94         for(int i=0;i<n-1;i++)
95             pd,write(ans[i]);
96         pn;
97     }
98     return 0;
99 }