Submission #633960

#	Time	Username	Problem	Language	Result	Execution time	Memory
633960		Ronin13	Split the Attractions (IOI19_split)	C++14	100 / 100	545 ms	77100 KiB

split

#include "split.h"
#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define f first
#define s second
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define epb emplace_back
using namespace std;

const int NMAX = 1e6 + 1;

int sz[NMAX], p[NMAX];
vector <vector <int> > g(NMAX);
vector <vector <int> > G(NMAX);
vector <bool> used(NMAX);
set <pii> edges;
set <pii> tree;
int t[NMAX];
int mx[NMAX];

void dfs(int v, int e = -1){
    used[v] = true;
    t[v] = 1;
    for(int to : g[v]){
        if(used[to]) continue;
        edges.erase({to, v});
        edges.erase({v, to});
        tree.insert({v, to});
        G[v].pb(to);
        G[to].pb(v);
        dfs(to);
        t[v] += t[to];
        mx[v] = max(mx[v], t[to]);
    }
}

int find_cen(int v, int n, int e = -1){
    if(2 * (n - t[v]) <= n){
        if(mx[v] * 2 <= n) return v;
    }
    for(int to : G[v]) {
        if(to == e) continue;
        int x = find_cen(to, n, v);
        if(x != -1) return x;
    }
    return -1;
}

void make_set(int v){
    p[v] = v;
    sz[v] = 1;
}

int find_set(int v){
    return (v == p[v]) ? v : p[v] = find_set(p[v]);
}

void union_sets(int a, int b){
    a = find_set(a);
    b = find_set(b);
    if(a == b) return ;
    if(sz[a] < sz[b])swap(a, b);
    p[b] = a;
    sz[a] += sz[b];
}

vector <int> ans;
int cnt = 0;

void getcmp(int v, int x, int a){

    cnt++;
    ans[v] = x;
    used[v] = true;
    if(cnt == a){
        return;
    }

    for(int to : G[v]){
        if(used[to]) continue;
        getcmp(to, x, a);
        if(cnt == a) return;
    }
}

vector<int> find_split(int n, int a, int b, int c, vector<int> p, vector<int> q) {
    for(int i = 0; i < p.size(); i++){
        int u = p[i], v = q[i];
        g[u].pb(v);
        g[v].pb(u);
        edges.insert({u, v});
    }
    dfs(0);
    int x = find_cen(0, n);
    for(int i = 0; i < n; i++){
        make_set(i);
    }
    for(auto to : tree){
        if((to.f != x) && (to.s != x)) union_sets(to.f, to.s);
    }
    vector <pii> vec;
    vec.pb({a, 1});
    vec.pb({b, 2});
    vec.pb({c, 3});
    sort(vec.begin(), vec.end());
    ans.resize(n);
    for(int i = 0; i < n; i++){
        ans[i] = vec[2].s;
    }
    bool ind = false;
    for(int i = 0; i < n; i++){
        if(i == x) continue;
        int xx = find_set(i);
        if(sz[xx] >= vec[0].f){
            for(int j = 0; j < n; j++) used[j] = false;
            used[x] = true;
            getcmp(xx, vec[0].s, vec[0].f);
            used[x] = false;
            cnt = 0;
            getcmp(x, vec[1].s, vec[1].f);
            ind = true;
            break;
        }
    }
    if(!ind){
        for(auto to : edges){
            int u = to.f, v = to.s;

            if(u == x || v == x) continue;
            G[v].pb(u);
            G[u].pb(v);
            union_sets(u, v);
            u = find_set(u);

            if(sz[u] >= vec[0].f){
                for(int j= 0; j < n; j++){
                    used[j] = false;
                }
                used[x] = true;
                getcmp(u, vec[0].s, vec[0].f);
                cnt = 0;
                used[x] = false;
                getcmp(x, vec[1].s, vec[1].f);
                ind = true;
                break;
            }
        }
    }
    if(!ind) {
        ans.assign(n, 0);
        return ans;
    }
    return ans;
}

Compilation message (stderr)

split.cpp: In function 'std::vector<int> find_split(int, int, int, int, std::vector<int>, std::vector<int>)':
split.cpp:90:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   90 |     for(int i = 0; i < p.size(); i++){
      |                    ~~^~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 11 / 11
• Subtask 3: 22 / 22
• Subtask 4: 24 / 24
• Subtask 5: 36 / 36