hdu 1874 畅通工程续 (Dijkstra or Floyd or Dfs)

 1 #include<cstring>
 2 #include<cstdio>
 3 #include<algorithm>
 4 using namespace std;
 5 #define mx 200000000;
 6 int map[205][205];
 7 int v[205],ans[205];
 8 int n;
 9 void f(int x)
10 {
11     v[x]=1;
12     int i,p,mn;
13     for (i=0;i<n;i++) ans[i]=map[x][i];
14     while (1)
15     {
16         p=x;
17         mn=mx
18         for (i=0;i<n;i++)
19         {
20             if (!v[i]&&mn>ans[i])
21             {
22                 p=i;
23                 mn=ans[i];
24             }
25         }
26         if (p==x) return ;
27         v[p]=1;
28         for (i=0;i<n;i++)
29         {
30             if (!v[i]&&ans[i]>ans[p]+map[p][i])
31                 ans[i]=ans[p]+map[p][i];
32         }
33     }
34 }
35 int main()
36 {
37     int m,i,j,a,b,c;
38     while (~scanf("%d%d",&n,&m))
39     {
40         memset(v,0,sizeof(v));
41         for (i=0;i<n;i++)
42         for (j=0;j<n;j++)
43         {
44             if (i==j) map[i][j]=0;
45             else map[i][j]=mx;
46         }
47         while (m--)
48         {
49             scanf("%d%d%d",&a,&b,&c);
50             if (map[a][b]>c)
51              map[a][b]=map[b][a]=c;
52         }
53         scanf("%d%d",&a,&b);
54         f(a);
55        if(ans[b]<200000000)
56           printf("%d\n",ans[b]);
57        else printf("-1\n");
58     }
59 }

 1 #include<cstring>
 2 #include<cstdio>
 3 #include<algorithm>
 4 using namespace std;
 5 #define mx 200000000;
 6 int map[205][205];
 7 int n;
 8 void f()
 9 {
10    int i,j,k;
11    for (k=0;k<n;k++)
12    for (i=0;i<n;i++)
13    for (j=0;j<n;j++)
14    if (map[i][j]>map[i][k]+map[k][j])
15    map[i][j]=map[i][k]+map[k][j];
16 }
17 int main()
18 {
19     int m,i,j,a,b,c;
20     while (~scanf("%d%d",&n,&m))
21     {
22         for (i=0;i<n;i++)
23         for (j=0;j<n;j++)
24         {
25             if (i==j) map[i][j]=0;
26             else map[i][j]=mx;
27         }
28         while (m--)
29         {
30             scanf("%d%d%d",&a,&b,&c);
31             if (map[a][b]>c)
32              map[a][b]=map[b][a]=c;
33         }
34        scanf("%d%d",&a,&b);
35        f();
36        if(map[a][b]<200000000)
37           printf("%d\n",map[a][b]);
38        else printf("-1\n");
39     }
40 }

 1 #include<cstring>
 2 #include<cstdio>
 3 #include<algorithm>
 4 using namespace std;
 5 #define mx 200000000;
 6 int map[205][205];
 7 int v[205];
 8 int ans;
 9 int n;
10 void dfs(int x,int y,int p)
11 {
12    if (p>ans) return ;
13    if (x==y)
14    {
15        ans=p;
16        return ;
17    }
18    int i;
19    for (i=0;i<n;i++)
20    {
21        if (v[i]!=-1&&map[x][i])
22        {
23            if (v[i]&&v[i]<=p+map[x][i]) continue;
24            v[i]=p+map[x][i];
25            dfs(i,y,p+map[x][i]);
26        }
27    }
28 }
29 int main()
30 {
31     int m,i,j,a,b,c;
32     while (~scanf("%d%d",&n,&m))
33     {
34         memset(v,0,sizeof(v));
35         for (i=0;i<n;i++)
36         for (j=0;j<n;j++) map[i][j]=0;
37         while (m--)
38         {
39             scanf("%d%d%d",&a,&b,&c);
40             if (map[a][b]>c||map[a][b]==0)
41              map[a][b]=map[b][a]=c;
42         }
43        scanf("%d%d",&a,&b);
44        ans=mx;
45        v[a]=-1;
46        dfs(a,b,0);
47        if(ans<200000000)
48           printf("%d\n",ans);
49        else printf("-1\n");
50     }
51 }