Submission #398044

#	Time	Username	Problem	Language	Result	Execution time	Memory
398044		ACmachine	Friend (IOI14_friend)	C++17	46 / 100	282 ms	65536 KiB

friend

#include "friend.h"
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using ordered_map = tree<T, U, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef long long ll;
typedef long double ld;

typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vi;
typedef vector<ll> vll;

#define FOR(i,j,k,in) for(int i=(j); i < (k);i+=in)
#define FORD(i,j,k,in) for(int i=(j); i >=(k);i-=in)
#define REP(i,b) FOR(i,0,b,1)
#define REPD(i,b) FORD(i,b,0,1)
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define all(x) begin(x), end(x)
#define MANY_TESTS int tcase; cin >> tcase; while(tcase--)

const double EPS = 1e-9;
const int MOD = 1e9+7;
const ll INFF = 1e18;
const int INF = 1e9;
const ld PI = acos((ld)-1);
const vi dy = {1, 0, -1, 0, -1, 1, 1, -1};
const vi dx = {0, 1, 0, -1, -1, 1, -1, 1};

void DBG(){cout << "]" << endl;}
template<typename T, typename ...U> void DBG(const T& head, const U... args){ cout << head << "; "; DBG(args...); }
#define dbg(...) cout << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__);
#define chk() cout << "Check at line(" << __LINE__ << ") hit." << endl;

template<class T, unsigned int U>
ostream& operator<<(ostream& out, const array<T, U> &v){out << "[";  REP(i, U) out << v[i] << ", ";  out << "]"; return out;}
template <class T, class U>
ostream& operator<<(ostream& out, const pair<T, U> &par) {out << "[" << par.first << ";" << par.second << "]"; return out;}
template <class T>
ostream& operator<<(ostream& out, const set<T> &cont) { out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template <class T, class U>
ostream& operator<<(ostream& out, const map<T, U> &cont) {out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template<class T>
ostream& operator<<(ostream& out, const vector<T> &v){ out << "[";  REP(i, v.size()) out << v[i] << ", ";  out << "]"; return out;}

template<class T>
istream& operator>>(istream& in, vector<T> &v){ for(auto &x : v) in >> x; return in; }

// dinic
// so long :(
struct flow_edge{
    int src, dest;
    int flow, cap;
};
struct flow_network{
    vector<vector<int>> g;
    vector<flow_edge> edges;
    vector<int> level, ptr;
    int s, t;
    int n;
    int m = 0;
    int maxF = INF;
    void add_edge(int u, int v, int cap){
        int id = edges.size();
        edges.pb({u, v, 0, cap});
        edges.pb({u, v, 0, 0});
        g[u].pb(m);
        g[v].pb(m + 1);
        m += 2;
    }
    flow_network(int _n, int _s, int _t) : n(_n), s(_s), t(_t){
        g.resize(n);
        level.resize(n);
        ptr.resize(n);
    }
    bool bfs(){
        fill(level.begin(), level.end(), -1);
        fill(ptr.begin(), ptr.end(), 0);
        level[s] = 0;
        queue<int> q;
        q.push(s);
        while(!q.empty()){
            int v = q.front();
            q.pop();
            for(int id : g[v]){
                auto e = edges[id];
                if(e.cap - e.flow < 1 || level[e.dest] != -1) continue;
                level[e.dest] = level[v] + 1;
                q.push(e.dest);
            }
        }
        return level[t] != -1;
    }
    int dfs(int v, int pushed){
        if(pushed == 0) return 0;
        if(v == t) return pushed;
        for(int& cid = ptr[v]; cid < g[v].size(); ++cid){
            int id = g[v][cid];
            auto &e1 = edges[id];
            auto &e2 = edges[id^1];
            if(level[e1.dest] != level[v] + 1 || e1.cap - e1.flow < 1) continue;
            int curr_pushed = dfs(e1.dest, min(pushed, e1.cap - e1.flow));
            if(curr_pushed == 0) continue;
            e1.flow += curr_pushed; e2.flow -= curr_pushed;
            return curr_pushed;
        }
        return 0;
    }
    int get_flow(){
        int res_flow = 0;
        while(true){
            if(!bfs()) break;
            int pushed;
            while(true){
                int pushed = dfs(s, maxF);
                res_flow += pushed;
                if(pushed == 0) break;
            }
        }
        return res_flow;
    }

};
// Find out best sample
int findSample(int n,int confidence[],int host[],int protocol[]){
	auto solve_1 = [&](){
	    vector<vector<int>> mat(n, vector<int>(n, 0));
	    vector<vector<int>> g(n);
	    auto join = [&](int u, int v){
	        g[u].pb(v);
	        g[v].pb(u);
	        mat[u][v] = mat[v][u] = 1;
	    };
	    FOR(i, 1, n, 1){
	        if(protocol[i] == 0){
                join(host[i], i);
	        }
	        else if(protocol[i] == 1){
	            for(int x : g[host[i]]){
	                join(x, i);
	            }
	        }
	        else{
	            for(int x : g[host[i]]){
	                join(x, i);
	            }
	            join(host[i], i);
	        }
	    }
	    int ans = 0;
	    REP(i, (1 << n)){
	        bool can = true;
	        int tm = 0;
	        REP(j, n){
	            if(i&(1 << j)){
	                tm += confidence[j];
	            }
	        }
	        REP(j, n){
	            REP(k, n){
	                if(j == k) continue;
	                if((i&(1 << j)) && (i&(1 << k))){
	                    if(mat[j][k])
	                        can = false;
	                }
	            }
	        }
	        if(can)
	            ans = max(ans, tm);
	    }
	    return ans;
	};
	auto solve_subtask_2 = [&](){
	    int ans = 0;
	    REP(i, n) ans += confidence[i];
	    return ans;
	};
	auto solve_subtask_3 = [&](){
	    int ans = 0;
	    REP(i, n) ans = max(ans, confidence[i]);
	    return ans;
	};
	auto solve_subtask_4 = [&](){
        vector<vector<int>> g(n);
        FOR(i, 1, n, 1){
            g[host[i]].pb(i);
            g[i].pb(host[i]);
        }
        vector<array<int, 2>> dp(n, {0, 0});
        function<void(int, int)> dfs = [&](int v, int p){
            for(int x : g[v]){
                if(x == p) continue;
                dfs(x, v);
            }
            dp[v][1] = confidence[v];
            for(int x : g[v]){
                if(x == p) continue;
                dp[v][1] += dp[x][0];
                dp[v][0] += max(dp[x][1], dp[x][0]);
            }
        };
        dfs(0, -1);
        return max(dp[0][0], dp[0][1]);
	};
	auto solve_subtask_5 = [&](){
	    // smh learn kuhn
	    // always bipartite
	    // max indep set = n - max matching
	    vector<vector<int>> g(n);
	    FOR(i, 1, n, 1){
	        if(protocol[i] == 0){
	            g[i].pb(host[i]);
	            g[host[i]].pb(i);
	        }
	        else{
	            for(int x : g[host[i]]){
	                g[x].pb(i);
	                g[i].pb(x);
	            }
	        }
	    }
	    flow_network mf(1005, 1001, 1002);
	    vector<int> dist(n, -1);
	    auto solve_component = [&](int s){
	        queue<int> q;
            dist[s] = 0;
            q.push(s);
            vector<int> curr_visited;
            while(!q.empty()){
                int v = q.front();
                curr_visited.pb(v);
                q.pop();
                for(int x : g[v]){
                    if(dist[x] == -1){
                        dist[x] = dist[v] + 1;
                    }
                }
            }
            for(int v : curr_visited){
                if(dist[v] % 2 == 1) {
                    mf.add_edge(v, mf.t, 1);
                    continue;
                }
                mf.add_edge(mf.s, v, 1);
                for(int x : g[v]){
                    mf.add_edge(v, x, 1);
                }
            }
	    };
	    REP(i, n){
	        if(dist[i] == -1){
	            solve_component(i);
	        }
	    }
	    int max_indep_set = n - mf.get_flow();
	    return max_indep_set;
	};
	bool sub2 = true;
	FOR(i, 1, n, 1){
	    if(protocol[i] != 1)
	        sub2 = false;
	}
	bool sub3 = true;
	FOR(i, 1, n, 1){
	    if(protocol[i] != 2)
	        sub3 = false;
	}
	bool sub4 = true;
	FOR(i, 1, n, 1){
	    if(protocol[i] != 0)
	        sub4 = false;
	}
	if(n <= 10) return solve_1();
	else if(sub2) return solve_subtask_2();
	else if(sub3) return solve_subtask_3();
	else if(sub4) return solve_subtask_4();
	else solve_subtask_5();
	//return ans;
}

Compilation message (stderr)

friend.cpp: In member function 'void flow_network::add_edge(int, int, int)':
friend.cpp:73:13: warning: unused variable 'id' [-Wunused-variable]
   73 |         int id = edges.size();
      |             ^~
friend.cpp: In constructor 'flow_network::flow_network(int, int, int)':
friend.cpp:69:9: warning: 'flow_network::n' will be initialized after [-Wreorder]
   69 |     int n;
      |         ^
friend.cpp:68:9: warning:   'int flow_network::s' [-Wreorder]
   68 |     int s, t;
      |         ^
friend.cpp:80:5: warning:   when initialized here [-Wreorder]
   80 |     flow_network(int _n, int _s, int _t) : n(_n), s(_s), t(_t){
      |     ^~~~~~~~~~~~
friend.cpp: In member function 'int flow_network::dfs(int, int)':
friend.cpp:106:36: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |         for(int& cid = ptr[v]; cid < g[v].size(); ++cid){
      |                                ~~~~^~~~~~~~~~~~~
friend.cpp: In member function 'int flow_network::get_flow()':
friend.cpp:122:17: warning: unused variable 'pushed' [-Wunused-variable]
  122 |             int pushed;
      |                 ^~~~~~
friend.cpp: In function 'int findSample(int, int*, int*, int*)':
friend.cpp:288:1: warning: control reaches end of non-void function [-Wreturn-type]
  288 | }
      | ^

• Subtask 1: 11 / 11
• Subtask 2: 8 / 8
• Subtask 3: 8 / 8
• Subtask 4: 19 / 19
• Subtask 5: 0 / 23
• Subtask 6: 0 / 31