Submission #999399

#	Time	Username	Problem	Language	Result	Execution time	Memory
999399		vjudge1	LOSTIKS (INOI20_lostiks)	C++17	0 / 100	32 ms	27988 KiB

Main

#include <bits/stdc++.h>
//#define int ll
#define MAX 1000001
#define INF INT_MAX
#define MOD 1000000007
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define ins insert
#define ff first
#define ss second 
#define all(a) a.begin(),a.end()
#define lb(a,b) lower_bound(all(a),b)
#define ub(a,b) upper_bound(all(a),b)
#define sortv(a) sort(all(a))
#define outputar(a,b){\
    for(int i=0;i<b;i++){\
        cout << a[i] << " ";\
    }\
    cout << endl;\
}
#define outputvec(a){\
    for(auto x:a){\
        cout << (int)x << " ";\
    }\
    cout << endl;\
}
#define reset(a,n,v){\
    for(int i=0;i<n;i++){\
        a[i]=v;\
    }\
}
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef tuple<ll,ll,ll> tll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef double db;
typedef long double ldb;
inline void USACO(string filename){
  freopen((filename+".in").c_str(),"r",stdin);
  freopen((filename+".out").c_str(),"w",stdout);
}
int n,q,t=1,m,k,x,y,z,x2,y2,z2,a[MAX],b[MAX],d[MAX];
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//string s[MAX],str[MAX];
//int e[1001][1001];
string s1,s2,s3;
const int mod = 998244353;
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};
vector<vector<int>> g;
int st[MAX][20],dep[MAX],pre[MAX],cnt=0;
int lca(int x,int y){
    if(dep[x]<dep[y]){
        swap(x,y);
    }
    int h=dep[x]-dep[y];
    for(int i=0;i<20;i++){
        if((h&(1<<i))){
            x=st[x][i];
        }
    }
    if(x==y){
        return x;
    }
    for(int i=19;i>=0;i--){
        if(st[x][i]!=st[y][i]){
            x=st[x][i];
            y=st[y][i];
        }
    }
    return pre[x];
}
vector<array<int,3>> c;
bool check(int x,int y,int z){
    bool ok=true;
    for(int i=0;i<cnt;i++){
        if(!(x&(1<<i))){
            int h1,h2,h3;
            h1=lca(c[i][0],y);
            h2=lca(c[i][0],z);
            h3=lca(y,z);
            if((h1==c[i][0] && dep[h1]>dep[h3]) || (h2==c[i][0] && dep[h2]>dep[h3])){
                ok=false;
            }
        }
    }
    return ok;
}
void dfs(int v,int prev){
    st[v][0]=prev;
    pre[v]=prev;
    for(auto x:g[v]){
        if(x==prev){
            continue;
        }
        dep[x]=dep[v]+1;
        dfs(x,v);
    }
}
int dp[1<<20][21];
void solve(){
    cin >> n;
    g.clear();
    g.resize(n+1);
    cin >> m >> k; 
    for(int i=0;i<n-1;i++){
        cin >> x >> y >> z;
        g[x].pb(y);
        g[y].pb(x);
        a[i]=z;
        if(a[i]!=0){
            c.pb({x,y,i});
            cnt++;
        }
    }
    dfs(1,-1);
    for(int i=1;i<20;i++){
        for(int j=1;j<=n;j++){
            if(st[j][i-1]!=-1){
                st[j][i]=st[st[j][i-1]][i-1];
            }
        }
    }
    for(int i=0;i<cnt;i++){
        int n1,n2; 
        n1=c[0][0];
        n2=c[0][1];
        if(dep[n1]<dep[n2]){
            swap(n1,n2);
        }
        c.pb({n1,n2,c[0][2]});
        c.erase(c.begin());
    }
    int h=(1<<cnt);
    for(int i=0;i<h;i++){
        for(int j=0;j<=cnt;j++){
            dp[i][j]=INF;
        }
    }
    dp[0][cnt]=0;
    int res=INF;
    for(int i=0;i<h;i++){
        for(int j=0;j<=cnt;j++){
            if(dp[i][j]==INF){
                continue;
            }
            int num; 
            if(j==cnt){
                num=m;
            }
            else{
                num=a[c[j][2]];
            }
            for(int z=0;z<cnt;z++){
                if(!(i&(1<<z)) && check(i,num,a[c[z][2]])){
                    dp[i+(1<<z)][z]=min(dp[i+(1<<z)][z],dp[i][j]+dep[num]+dep[a[c[z][2]]]-2*dep[lca(num,a[c[z][2]])]);
                }
            }
            if(check(i,num,k)){
                res=min(res,dp[i][j]+dep[num]+dep[k]-2*dep[lca(num,k)]); 
            }
        }
    }
    if(res==INF){
        res=-1;
    }
    cout << res << "\n";
}
signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    //freopen("input13.txt","r",stdin);
    //cin >> t;
    ll cnt1=1;
    while(t--){
        solve();
        cnt1++; 
    }
}

• Subtask 1: 0 / 23
• Subtask 2: 0 / 36
• Subtask 3: 0 / 41