Submission #720526

#	Time	Username	Problem	Language	Result	Execution time	Memory
720526		Jarif_Rahman	Simurgh (IOI17_simurgh)	C++17	19 / 100	997 ms	6104 KiB

simurgh

#include "simurgh.h"
#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;

struct dsu{
    int n;
    vector<int> sz, p;
    dsu(int _n): n(_n){
        sz.resize(n, 1);
        p.resize(n);
        for(int i = 0; i < n; i++) p[i] = i;
    }
    int get(int x){
        if(p[x] != x) p[x] = get(p[x]);
        return p[x];
    }
    bool unite(int a, int b){
        a = get(a), b  = get(b);
        if(a == b) return 0;
        if(sz[b] > sz[a]) swap(a, b);
        sz[a]+=sz[b];
        sz[b] = 0;
        p[b] = a;
        return 1;
    }
};

int n, m;
vector<int> U, V;
vector<int> royal;
vector<vector<pair<int, int>>> graph;

vector<int> generate_tree(vector<int> E){
    dsu ds(n);
    vector<int> T;
    for(int i: E){
        if(ds.unite(U[i], V[i])) T.pb(i);
        else return {};
    }
    for(int i = 0; i < m; i++) if(ds.unite(U[i], V[i])) T.pb(i);
    return T;
}
int replacement_edge(vector<int> E, int i){
    dsu ds(n);
    for(int j: E) if(j != i) ds.unite(U[j], V[j]);
    for(int j = 0; j < m; j++) if(j != i && ds.unite(U[j], V[j])) return j;
    return -1;
}
int count_extra_royal(vector<int> T, vector<int> C){
    dsu ds(n);
    int c = 0;
    vector<int> q;
    for(int i: C) ds.unite(U[i], V[i]), q.pb(i);
    for(int i: T) if(ds.unite(U[i], V[i])) c+=max(royal[i], 0), q.pb(i);
    return count_common_roads(q)-c;
}

vector<int> find_roads(int _n, vector<int> _U, vector<int> _V){
    swap(n, _n), swap(U, _U), swap(V, _V);
    m = U.size();
    royal.assign(m, -1);
    graph.resize(n);

    for(int i = 0; i < m; i++){
        graph[U[i]].pb({V[i], i});
        graph[V[i]].pb({U[i], i});
    }

    vector<int> A, B;
    int e = 0;
    while(1){
        vector<int> C = A;
        for(int i: B) C.pb(i);
        int ei = C.size();
        C.pb(e);

        if(C.size() == n-1){
            int cnt = 0;
            for(int i = 0; i < A.size(); i++) if(royal[A[i]] == 1) cnt++;
            int x = count_common_roads(C);
            for(int i: B) A.pb(i);
            A = C;
            for(int i: B) royal[i] = (x > cnt);
            royal[e] = (x > cnt);
            break;
        }

        auto T = generate_tree(C);
        int i = replacement_edge(T, e);

        if(i == -1){
            for(int j: B) royal[j] = 1;
            royal[e] = 1;
            A.insert(A.end(), B.begin(), B.end());
            B.clear();
            A.pb(e);
            if(ei == n-2) break;
            e = T[ei+1];
            continue;
        }
        int x = count_common_roads(T);
        T[ei] = i;
        int y = count_common_roads(T);
        T[ei] = e;

        if(x > y){
            for(int j: B) royal[j] = 1;
            royal[e] = 1;
            royal[i] = 0;
            A.insert(A.end(), B.begin(), B.end());
            B.clear();
            A.pb(e);
            if(ei == n-2) break;
            e = T[ei+1];
        }
        else if(x < y){
            for(int j: B) royal[j] = 0;
            royal[e] = 0;
            royal[i] = 1;
            A.insert(A.end(), B.begin(), B.end());
            B.clear();
            A.pb(e);
            if(ei == n-2) break;
            e = T[ei+1];
        }
        else{
            if(royal[i] != -1){
                for(int j: B) royal[j] = royal[i];
                royal[e] = royal[i];
                A.insert(A.end(), B.begin(), B.end());
                B.clear();
                A.pb(e);
                if(ei == n-2) break;
                e = T[ei+1];
                continue;
            }
            C.pb(i);
            auto T2 = generate_tree(C);
            if(T2.empty()){
                for(int j: B) royal[j] = 0;
                royal[e] = 0;
                royal[i] = 0;
                A.insert(A.end(), B.begin(), B.end());
                B.clear();
                A.pb(e);
                if(ei == n-2) break;
                e = T[ei+1];
            }
            else{
                B.pb(e);
                e = i;
            }
        }
    }

    vector<int> ans;
    for(int i = 0; i < m; i++) if(royal[i] == 1) ans.pb(i);

    for(int nd = 0; nd < n; nd++){
        vector<int> S;
        for(auto [x, i]: graph[nd]) if(royal[i] == -1) S.pb(i);
        if(S.empty()) continue;
        int X = count_extra_royal(A, S);
        while(X > 0){
            int a = 0, b = int(S.size())-1;
            while(a < b){
                vector<int> s;
                int md = (a+b)/2;
                for(int j = 0; j <= md; j++) s.pb(S[j]);
                int x = count_extra_royal(A, s);
                if(x >= X) b = md;
                else a = md+1;
            }
            royal[S[a]] = 1;
            ans.pb(S[a]);
            X--;
        }
        for(int i: S) if(royal[i] == -1) royal[i] = 0;
    }

    return ans;
}

Compilation message (stderr)

simurgh.cpp: In function 'std::vector<int> find_roads(int, std::vector<int>, std::vector<int>)':
simurgh.cpp:82:21: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   82 |         if(C.size() == n-1){
      |            ~~~~~~~~~^~~~~~
simurgh.cpp:84:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   84 |             for(int i = 0; i < A.size(); i++) if(royal[A[i]] == 1) cnt++;
      |                            ~~^~~~~~~~~~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 17
• Subtask 3: 0 / 21
• Subtask 4: 19 / 19
• Subtask 5: 0 / 30