poj 1161 最短路构图

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <queue>
#include <vector>

#define maxn 400
#define INF  0x3f3f3f
#define min(a,b) (a>b?b:a)
using namespace std;

int first[maxn][maxn];
int d[maxn][maxn];
vector<int> G[maxn];
int N,M,L;
int mem[35];

void floyd(){
for(int k=1;k<=M;k++)
for(int i=1;i<=M;i++){
for(int j=1;j<=M;j++){
d[i][j] = min(d[i][j],d[i][k]+d[k][j]);
}
}
}
int main()
{
scanf("%d%d%d",&M,&N,&L);
for(int i=1;i<=L;i++){
scanf("%d",&mem[i]);
}
memset(first,0,sizeof(first));
memset(d,0x3f,sizeof(d));
for(int i=1;i<=M;i++){
int k,a,b,c;
scanf("%d%d",&k,&a);
G[a].push_back(i);
k--;   b = a;
while(k--){
scanf("%d",&c);
G[c].push_back(i);
if(!first[b][c])
first[b][c] = first[c][b] = i;
else{
d[first[b][c]][i] = d[i][first[c][b]] = 1;  //复制粘贴的代码太可怕了
}
b = c;
}
if(!first[a][b])
first[a][b] = first[b][a] = i;
else{
d[first[a][b]][i] = d[i][first[a][b]] = 1;
}
}

for(int i=1;i<=M;i++) d[i][i] = 0;
floyd();

int ans = INF;
for(int i=1;i<=M;i++){
int sum = 0;
for(int j=1;j<=L;j++){
int u = mem[j];
int mincross = INF;
for(int k=0;k<G[u].size();k++){
int v = G[u][k];
mincross = min(mincross,d[v][i]);
}
sum += mincross;
}
ans = min(ans,sum);
}
printf("%d\n",ans);
}