#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fr first
#define sc second
const int mxn=1e6+5,sz=(1<<20);
int n,dis[40][40],par[mxn][22],c[mxn],key[25],door[25],cnt=0,d[mxn];
ll dp[sz][25],ans=1e9;
vector<pair<int,int>>v[mxn];
void dfs(int z,int f=0){
for(int i=1;i<=20;i++)
par[z][i]=par[par[z][i-1]][i-1];
for(auto i:v[z]){
if(par[z][0]!=i.fr){
par[i.fr][0]=z;
c[i.fr]=c[z];
d[i.fr]=d[z]+1;
if(i.sc){
door[++cnt]=z;
key[cnt]=i.sc;
c[i.fr]|=(1<<(cnt-1));
}
dfs(i.fr);
}
}
}
int lca(int x,int y){
if(x==0 || y==0)return 0;
if(d[x]<d[y])swap(x,y);
int res=0;
for(int i=20;i>=0;i--){
if((1<<i)<=d[x]-d[y])x=par[x][i],res+=(1<<i);
}
if(x==y)return res;
for(int i=20;i>=0;i--){
if(par[x][i]!=par[y][i])x=par[x][i],y=par[y][i],res+=(1<<(i+1));
}
return res+2;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n;
cin>>door[21]>>key[21];
for(int i=1;i<n;i++){
int x,y,w;
cin>>x>>y>>w;
v[x].push_back({y,w});
v[y].push_back({x,w});
}
dfs(door[21]);
for(int i=1;i<=21;i++){
for(int j=1;j<=21;j++){
dis[i][j]=lca(door[i],key[j]);
}
}
for(int i=0;i<cnt;i++){
if(!c[door[i+1]] && !c[key[i+1]])
dp[(1<<i)][i]=dis[21][i+1]+dis[i+1][i+1];
else
dp[(1<<i)][i]=1e9;
}
for(int i=1;i<(1<<cnt);i++){
for(int j=0;j<cnt;j++){
dp[i][j]=1e9;
if((i&(1<<j)) && (i&c[door[j+1]])==c[door[j+1]] && (i&c[key[j+1]])==c[key[j+1]]) {
for(int w=0;w<cnt;w++){
if(i&(1<<w)){
if(w!=j ){
dp[i][j]=min(dp[i][j],dis[j+1][j+1]+dis[w+1][j+1]+dp[i-(1<<j)][w]);
}
}
}
if((i&(c[key[21]]))==c[key[21]]){
ans=min(ans,dp[i][j]+dis[j+1][21]);
}
}
}
}
if(c[key[21]]==0)ans=dis[21][21];
assert(ans>=0);
cout<<ans;
return 0;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
6 ms |
27224 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
6 ms |
27228 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
6 ms |
27224 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
