Submission #428252

#	Time	Username	Problem	Language	Result	Execution time	Memory
428252		juggernaut	Capital City (JOI20_capital_city)	C++17	100 / 100	684 ms	123804 KiB

capital_city

#include<bits/stdc++.h>
#define fr first
#define sc second
using namespace std;
void usaco(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
typedef long long ll;
#define USING_ORDERED_SET 0
#if USING_ORDERED_SET
#include<bits/extc++.h>
using namespace __gnu_pbds;
template<class T>using ordered_set=tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
#endif
template<class T>void umax(T &a,T b){if(a<b)a=b;}
template<class T>void umin(T &a,T b){if(b<a)a=b;}
#ifdef IOI2021SG
    #define printl(args...)printf(args)
#else
    #define printl(args...)((void)0)
#endif
int n,k;
int tin[200005],tout[200005],timer,up[200005][18];
vector<int>g[200005],color[200005],g1[200005],g2[200005];

int mn[200005][18];
int mx[200005][18];
int a[200005];
void dfs(int v,int p){
    tin[v]=++timer;
    up[v][0]=p;
    mn[v][0]=::a[v];
    mx[v][0]=::a[v];
    for(int i=1;i<18;i++){
        up[v][i]=up[up[v][i-1]][i-1];
        mn[v][i]=min(mn[v][i-1],mn[up[v][i-1]][i-1]);
        mx[v][i]=max(mx[v][i-1],mx[up[v][i-1]][i-1]);
    }
    for(int to:g[v])if(to!=p)dfs(to,v);
    tout[v]=++timer;
}
bool upper(int a,int b){
    return tin[a]<=tin[b]&&tout[a]>=tout[b];
}
int lca(int a,int b){
    if(upper(a,b))return a;
    if(upper(b,a))return b;
    for(int i=17;i>=0;i--)if(!upper(up[a][i],b))a=up[a][i];
    return up[a][0];
}
int lca(vector<int>&vec){
    int l=vec[0];
    for(int i=1;i<(int)vec.size();i++)l=lca(l,vec[i]);
    return l;
}
unordered_map<int,bool>vs[200005];
vector<pair<int,int>>edges;
void add_edge(int a,int b){
    if(a^b){
        if(vs[a][b])return;
        vs[a][b]=true;
        edges.emplace_back(a,b);
        g1[a].push_back(b);
    }
}
void add(int v,int a,int l){
    for(int i=17;i>=0;i--)
        if(mx[a][i]==mn[a][i])a=up[a][i];
    if(upper(a,l)&&a!=l)return;
    add_edge(v,::a[a]);
}
int cnt=0;
bool vis[200005];
int low[200005],_up[200005],tt,last;
int sz[200005];
stack<int>ss;
int id[200005];
bool used[200005];
void run(int u,int p=-1){
    low[u]=_up[u]=tt++;
    used[u]=1;
    ss.push(u);
    for(auto x:g1[u])
        if(used[x] && !id[x])umin(low[u],_up[x]);
        else if(!id[x]) run(x,u),umin(low[u],low[x]);
    if(low[u] == _up[u]){
        int cur; ++last;
        do{
            cur=ss.top();ss.pop();
            id[cur]=last;
            sz[last]++;
        }while(cur != u);
    }
}
int dp[200005];
int goo(int v){
    if(~dp[v])return dp[v];
    dp[v]=sz[v];
    for(int to:g2[v])dp[v]+=goo(to);
    return dp[v];
}
int main(){
    memset(dp,-1,sizeof dp);
    scanf("%d%d",&n,&k);
    for(int i=1;i<n;i++){
        int x,y;
        scanf("%d%d",&x,&y);
        g[x].push_back(y);
        g[y].push_back(x);
    }
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
        color[a[i]].push_back(i);
    }
    dfs(1,1);
    for(int i=1;i<=k;i++){
        int l=lca(color[i]);
        for(int j=0;j<(int)color[i].size();j++)add(i,color[i][j],l);
    }
    for(int i=1;i<=k;i++)if(!used[i])run(i);
    for(auto to:edges)if(id[to.fr]^id[to.sc]){
        g2[id[to.fr]].push_back(id[to.sc]);
    }
    int ans=k;
    for(int i=1;i<=last;i++)umin(ans,goo(i));
    printf("%d",ans-1);
}

Compilation message (stderr)

capital_city.cpp: In function 'void usaco(std::string)':
capital_city.cpp:5:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    5 | void usaco(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
capital_city.cpp:5:66: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    5 | void usaco(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
      |                                                           ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
capital_city.cpp: In function 'int main()':
capital_city.cpp:102:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |     scanf("%d%d",&n,&k);
      |     ~~~~~^~~~~~~~~~~~~~
capital_city.cpp:105:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  105 |         scanf("%d%d",&x,&y);
      |         ~~~~~^~~~~~~~~~~~~~
capital_city.cpp:110:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  110 |         scanf("%d",&a[i]);
      |         ~~~~~^~~~~~~~~~~~

• Subtask 1: 1 / 1
• Subtask 2: 10 / 10
• Subtask 3: 30 / 30
• Subtask 4: 59 / 59