Submission #427942

#	Time	Username	Problem	Language	Result	Execution time	Memory
427942		juggernaut	Capital City (JOI20_capital_city)	C++17	1 / 100	3117 ms	305176 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 a[200005];
void dfs(int v,int p){
    tin[v]=++timer;
    up[v][0]=p;
    for(int i=1;i<18;i++)up[v][i]=up[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];
}
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);
        g2[b].push_back(a);
    }
}
void add(int v,int a,int b){
    int lca=::lca(a,b);
    while(a!=lca){
        a=up[a][0];
        add_edge(v,::a[a]);
    }
    while(b!=lca){
        b=up[b][0];
        add_edge(v,::a[b]);
    }
}
bool vis[200005];
vector<int>ordr,comp;
void dfs1(int v){
    vis[v]=true;
    for(int to:g1[v])if(!vis[to])dfs1(to);
    ordr.push_back(v);
}
void dfs2(int v){
    comp.push_back(v);
    vis[v]=true;
    for(int to:g2[v])if(!vis[to])dfs2(to);
}
int sz[200005];
int dp[200005];
int id[200005];
int go(int v){
    if(~dp[v])return dp[v];
    dp[v]=sz[v];
    for(int to:g[v])dp[v]+=go(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++)
        for(int j=1;j<color[i].size();j++)add(i,color[i][0],color[i][j]);
    for(int i=1;i<=k;i++)if(!vis[i])dfs1(i);
    memset(vis,0,sizeof vis);
    timer=0;
    for(int i=0;i<k;i++)if(!vis[ordr[k-i-1]]){
        comp.clear();
        dfs2(ordr[k-i-1]);
        timer++;
        sz[timer]=comp.size();
        for(int to:comp)id[to]=timer;
    }
    for(int i=1;i<=timer;i++)g[i].clear(),vis[i]=0;
    for(int i=1;i<=n;i++)vs[i].clear();
    for(auto to:edges)
        if(id[to.fr]!=id[to.sc]){
            if(vs[id[to.fr]][id[to.sc]])continue;
            vs[id[to.fr]][id[to.sc]]=1;
            g[id[to.fr]].push_back(id[to.sc]);
        }
    int ans=k;
    for(int i=1;i<=timer;i++)umin(ans,go(i));
    printf("%d",ans-1);
}

Compilation message (stderr)

capital_city.cpp: In function 'int main()':
capital_city.cpp:98:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   98 |         for(int j=1;j<color[i].size();j++)add(i,color[i][0],color[i][j]);
      |                     ~^~~~~~~~~~~~~~~~
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:85:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   85 |     scanf("%d%d",&n,&k);
      |     ~~~~~^~~~~~~~~~~~~~
capital_city.cpp:88:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   88 |         scanf("%d%d",&x,&y);
      |         ~~~~~^~~~~~~~~~~~~~
capital_city.cpp:93:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |         scanf("%d",&a[i]);
      |         ~~~~~^~~~~~~~~~~~

• Subtask 1: 1 / 1
• Subtask 2: 0 / 10
• Subtask 3: 0 / 30
• Subtask 4: 0 / 59