M¹nh D¬ng Biªn So¹n Bé M«n CÊu Tróc D÷ LiÖu Gi¶i ThuËt 2012 §ª Sè 21 Trong Bé §Ò ¤n TËp #include<iostream.h> #include<conio.h> #include<fstream.h> ifstream Tepvao("C:/cau truc du lieu/dethi/dothi21.in.txt"); ofstream Tepra("C:/cau truc du lieu/dethi/kequa21.out.txt"); int x[100]; /* Thuat toan Djkstra tim duong di ngan nhat giua hai diem p q */ int kt(int i,int S[],int n) { for(int j=0;j<=n;j++) if(S[j]==i)return 0; return 1; } int dem=1; void DFS(int i,int a[][100],int n,int k) { x[i]=1; for(int j=1;j<=n;j++) if(x[j]==0&&a[i][j]==1){if(j==k){dem=0;return;} DFS(j,a,n,k);} } int KT(int i,int j,int n,int a[][100]) { dem=1; DFS(i,a,n,j); if(dem==1)return 0; return 1; } void Djkstra() { int W[100][100],S[100],P[100],D[100],X[100]; int n; Tepvao>>n; int a,b; Tepvao>>a; Tepvao>>b; for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) { Tepvao>>W[i][j]; } if(KT(a,b,n,W)==0){Tepra<<-1<<endl;return;} S[0]=a; D[a]=0; int nmin=0; for(int i=1;i<=n;i++) for(int j=1;j<=n;j++) if(W[i][j]>nmin)nmin=W[i][j]; nmin=nmin*n; for(int i=1;i<=n;i++) if(i!=a&&W[a][i]!=0) { D[i]=W[a][i]; P[i]=a; } else if(i!=a&&W[a][i]==0) { D[i]=0; } int min; min=nmin; for(int i=1;i<=n;i++) if(i!=a&&D[i]<min&&D[i]!=0){min=D[i];X[1]=i;} int dem=1; S[1]=X[1]; while(S[dem]!=b) { int XX=D[X[dem]]; for(int i=1;i<=n;i++) if(kt(i,S,dem)==1&&W[X[dem]][i]!=0) { if(D[i]==-1) { D[i]=XX+W[X[dem]][i]; P[i]=X[dem]; } else if(D[i]>XX+W[X[dem]][i]) { D[i]=XX+W[X[dem]][i]; P[i]=X[dem]; } } min=nmin; for(int i=1;i<=n;i++) if(kt(i,S,dem)==1&&min>D[i]&&D[i]!=0) {X[dem+1]=i;min=D[i];} dem=dem+1; S[dem]=X[dem]; } Tepra<<D[b]<<endl; int XX;X[0]=b; dem=0;XX=b; while(XX!=a) { dem++; XX=P[XX]; X[dem]=XX; } for(int i=dem;i>=0;i ) Tepra<<X[i]<<" "; Tepra<<endl; return ; } main() { Djkstra(); } . TËp #include<iostream.h> #include<conio.h> #include<fstream.h> ifstream Tepvao("C:/cau truc du lieu/dethi/dothi21.in.txt"); ofstream Tepra("C:/cau truc du lieu/dethi/kequa21.out.txt"); int x[100]; /* Thuat toan Djkstra