郊区春游
题解:
TSP问题。先把几个去的郊区的两两最短距离算出来,然后就是状压DP的过程了。
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 210,MAXR = 16;
int n, m, R, dst[MAXR];
int dis[MAXN][MAXN];
int f[1 << MAXR][MAXR];
void floyd() {
for (int k = 1; k <= n; k++)
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
dis[i][j] = min(dis[i][j], dis[i][k] + dis[k][j]);
return ;
}
int main() {
memset(dis, 0x3f, sizeof(dis));
memset(f, 0x3f, sizeof(f));
scanf("%d %d %d", &n, &m, &R);
for (int i = 1; i <= R; i++)
scanf("%d", &dst[i]);
for (int i = 1; i <= n; i++)
dis[i][i] = 0;
for (int i = 1, a, b, c; i <= m; i++) {
scanf("%d %d %d", &a, &b, &c);
dis[a][b] = dis[b][a] = min(dis[a][b], c);
}
floyd();
for (int i = 1; i <= R; i++)
f[1 << (i - 1)][i] = 0;
for(int i=1;i<(1<<R);i++){
for(int j=1;j<=R;j++){
if(i & (1 << (j - 1))){
for(int k=1;k<=R;k++){
if(!(i & (1 << (k - 1)))){
int state=i|(1<<(k-1));
f[state][k]=min(f[state][k],f[i][j]+dis[dst[j]][dst[k]]);
}
}
}
}
}
int ans = 0x3f3f3f3f;
for (int i = 1; i <= R; i++)
ans = min(ans, f[(1 << R) - 1][i]);
printf("%d", ans);
return 0;
}