Submission #104542

#	Time	Username	Problem	Language	Result	Execution time	Memory
104542		nikolapesic2802	Mergers (JOI19_mergers)	C++14	100 / 100	1122 ms	77276 KiB

mergers

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>

#define ll long long
#define pb push_back
#define sz(x) (int)(x).size()
#define mp make_pair
#define f first
#define s second
#define all(x) x.begin(), x.end()
#define D(x) cerr << #x << " is " << (x) << "\n";

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>; ///find_by_order(),order_of_key()
template<class T1, class T2> ostream& operator<<(ostream& os, const pair<T1,T2>& a) { os << '{' << a.f << ", " << a.s << '}'; return os; }
template<class T> ostream& operator<<(ostream& os, const vector<T>& a){os << '{';for(int i=0;i<sz(a);i++){if(i>0&&i<sz(a))os << ", ";os << a[i];}os<<'}';return os;}
template<class T> ostream& operator<<(ostream& os, const set<T>& a) {os << '{';int i=0;for(auto p:a){if(i>0&&i<sz(a))os << ", ";os << p;i++;}os << '}';return os;}
template<class T> ostream& operator<<(ostream& os, const multiset<T>& a) {os << '{';int i=0;for(auto p:a){if(i>0&&i<sz(a))os << ", ";os << p;i++;}os << '}';return os;}
template<class T1,class T2> ostream& operator<<(ostream& os, const map<T1,T2>& a) {os << '{';int i=0;for(auto p:a){if(i>0&&i<sz(a))os << ", ";os << p;i++;}os << '}';return os;}

const int N=5e5+5;
struct dsu{
    vector<int> par;
    void init()
    {
        par.resize(N);
        for(int i=0;i<N;i++)
            par[i]=i;
    }
    int find(int tr)
    {
        if(par[tr]==tr)
            return tr;
        return par[tr]=find(par[tr]);
    }
    void merge(int a,int b)
    {
        a=find(a);
        b=find(b);
        if(a==b)
            return;
        par[b]=a;
    }
}d;
vector<int> up(N),depth(N);
vector<vector<int> > graf(N);
void setup(int tr)
{
    for(auto p:graf[tr])
    {
        if(p==up[tr])
            continue;
        depth[p]=depth[tr]+1;
        up[p]=tr;
        setup(p);
    }
}
void merge(int a,int b)
{
    a=d.find(a);b=d.find(b);
    while(a!=b)
    {
        if(depth[a]<depth[b])
            swap(a,b);
        d.merge(up[a],a);
        a=d.find(up[a]);
    }
    /*while(d.find(a)!=d.find(b))
    {
        if(depth[a]<depth[b])
            swap(a,b);
        d.merge(a,b);
        a=up[a];
    }*/
}
int main()
{
    d.init();
    int n,k;
    scanf("%i %i",&n,&k);
    for(int i=1;i<n;i++)
    {
        int a,b;
        scanf("%i %i",&a,&b);
        a--;
        b--;
        graf[a].pb(b);
        graf[b].pb(a);
    }
    setup(0);
    vector<vector<int> > group(k);
    for(int i=0;i<n;i++)
    {
        int a;
        scanf("%i",&a);
        a--;
        group[a].pb(i);
    }
    for(int i=0;i<k;i++)
        for(int j=1;j<group[i].size();j++)
            merge(group[i][0],group[i][j]);
    int sol=0;
    vector<int> deg(n);
    for(int i=0;i<n;i++)
        for(auto p:graf[i])
            if(d.find(i)!=d.find(p))
            {
                if(deg[d.find(i)]==0)
                    sol++;
                if(deg[d.find(i)]==1)
                    sol--;
                deg[d.find(i)]++;
            }
    printf("%i\n",(sol+1)/2);
    return 0;
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:106:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=1;j<group[i].size();j++)
                     ~^~~~~~~~~~~~~~~~
mergers.cpp:86:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%i %i",&n,&k);
     ~~~~~^~~~~~~~~~~~~~~
mergers.cpp:90:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%i %i",&a,&b);
         ~~~~~^~~~~~~~~~~~~~~
mergers.cpp:101:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%i",&a);
         ~~~~~^~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 14 / 14
• Subtask 4: 22 / 22
• Subtask 5: 30 / 30