第一题：[USACO08OPEN] Clear And Present Danger S

 

#include<bits/stdc++.h>
using namespace std;
int n,m;
int g[105][105];
int arr[100005];
long long sum;
int main()
{scanf("%d%d",&n,&m);for(int i=1;i<=m;i++){scanf("%d",&arr[i]);}for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){scanf("%d",&g[i][j]);}}for(int k=1;k<=n;k++){for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){if(g[i][j]>g[i][k]+g[k][j]){g[i][j]=g[i][k]+g[k][j];}}}}int a=1,b=0;for(int i=1;i<=m;i++){b=arr[i];sum+=g[a][b];a=b;}printf("%lld",sum);return 0;
}

 

第二题：传送闭包 

 

#include<bits/stdc++.h>
using namespace std;
int n;
int g[105][105];
int main()
{scanf("%d",&n);for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){scanf("%d",&g[i][j]);}}for(int k=1;k<=n;k++){for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){g[i][j]=max(g[i][j],g[i][k]&g[k][j]);}}}for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){printf("%d ",g[i][j]);}printf("\n");}return 0;} 

第三题：传送门 

 

 

#include<bits/stdc++.h>
using namespace std;
int n,m;
int a[105][105];
void floyd()
{for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){for(int k=1;k<=n;k++){if(a[j][k]>a[j][i]+a[i][k])a[j][k]=a[j][i]+a[i][k];}}}
}int main()
{scanf("%d%d",&n,&m);for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){if(i==j)a[i][j]=0;elsea[i][j]=0x3f3f3f3f;}}int x,y,z;for(int i=0;i<m;i++){scanf("%d%d%d",&x,&y,&z);a[x][y]=a[y][x]=z;}floyd();long long sum=0x3f3f3f3f;for(int i=1;i<=n;i++){for(int j=1+i;j<=n;j++){long long sum2=0;for(int p=1;p<=n;p++){for(int q=1+p;q<=n;q++){sum2+=min(a[p][q],min(a[p][i]+a[j][q],a[p][j]+a[i][q]));}}sum=min(sum,sum2);}}printf("%lld",sum);return 0;
}