Submission #1070593

#	Time	Username	Problem	Language	Result	Execution time	Memory
1070593		GrindMachine	The Ties That Guide Us (CEOI23_incursion)	C++17	100 / 100	308 ms	10844 KiB

incursion

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

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

/*

read the edi a long time ago, dont really remember much from there

*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

#include "incursion.h"

std::vector<int> mark(std::vector<std::pair<int, int>> F, int safe) {
    // return {2, 2, 0};
    int n = sz(F)+1;
    vector<vector<int>> adj(n+5);
    for(auto [u,v] : F){
        adj[u].pb(v), adj[v].pb(u);
    }

    vector<int> par(n+5), subsiz(n+5);

    auto dfs = [&](int u, int p, auto &&dfs) -> void{
        par[u] = p;
        subsiz[u] = 1;
        trav(v,adj[u]){
            if(v == p) conts;
            dfs(v,u,dfs);
            subsiz[u] += subsiz[v];
        }
    };

    dfs(1,-1,dfs);

    vector<int> centroids;
    rep1(u,n){
        bool ok = true;
        trav(v,adj[u]){
            int s = subsiz[v];
            if(v == par[u]){
                s = n-subsiz[u];
            }
            if(s > n/2){
                ok = false;
            }
        }

        if(ok){
            centroids.pb(u);
        }
    }

    int siz = sz(centroids);
    assert(siz >= 1 and siz <= 2);

    auto can_reach = [&](int u, int p, auto &&can_reach) -> bool{
        bool ok = false;
        if(u == safe) ok = true;
        trav(v,adj[u]){
            if(v == p) conts;
            if(count(all(centroids),v)) conts;
            ok |= can_reach(v,u,can_reach);
        }
        return ok;
    };

    int r = -1;
    if(siz == 1){
        r = centroids[0];
    }
    else{
        rep(j,2){
            if(can_reach(centroids[j],-1,can_reach)){
                assert(r == -1);
                r = centroids[j];
            }
        }
    }

    assert(r != -1);
    dfs(r,-1,dfs);

    vector<int> ans(n);
    while(safe != -1){
        ans[safe-1] = 1;
        safe = par[safe];
    }

    return ans;
}

void locate(std::vector<std::pair<int, int>> F, int curr, int cnt) {
    int n = sz(F)+1;
    vector<vector<int>> adj(n+5);
    for(auto [u,v] : F){
        adj[u].pb(v), adj[v].pb(u);
    }

    vector<int> par(n+5), subsiz(n+5);

    auto dfs = [&](int u, int p, auto &&dfs) -> void{
        par[u] = p;
        subsiz[u] = 1;
        trav(v,adj[u]){
            if(v == p) conts;
            dfs(v,u,dfs);
            subsiz[u] += subsiz[v];
        }
    };

    dfs(1,-1,dfs);

    vector<int> centroids;
    rep1(u,n){
        bool ok = true;
        trav(v,adj[u]){
            int s = subsiz[v];
            if(v == par[u]){
                s = n-subsiz[u];
            }
            if(s > n/2){
                ok = false;
            }
        }

        if(ok){
            centroids.pb(u);
        }
    }

    int siz = sz(centroids);
    assert(siz >= 1 and siz <= 2);

    int r = centroids[0];
    dfs(r,-1,dfs);

    if(siz == 1){
        while(!cnt){
            cnt = visit(par[curr]);
            curr = par[curr];
        }

        while(true){
            vector<pii> ord;
            trav(v,adj[curr]){
                if(v == par[curr]) conts;
                ord.pb({subsiz[v],v});
            }
            sort(rall(ord));

            int nxt = -1;
            for(auto [s,v] : ord){
                int x = visit(v);
                if(x){
                    nxt = v;
                    break;
                }
                visit(curr);
            }

            if(nxt == -1) break;
            curr = nxt;
        }

        return;
    }

    while(!cnt){
        if(curr == r){
            curr = centroids[0]^centroids[1]^curr;
            visit(curr);
            break;
        }

        cnt = visit(par[curr]);
        curr = par[curr];
    }

    while(true){
        vector<pii> ord;
        trav(v,adj[curr]){
            if(v == par[curr]) conts;
            ord.pb({subsiz[v],v});
        }

        sort(rall(ord));

        int nxt = -1;
        for(auto [s,v] : ord){
            int x = visit(v);
            if(x){
                nxt = v;
                break;
            }
            visit(curr);
        }

        if(nxt == -1) break;
        curr = nxt;
    }

    // int x;
    // x = visit(3);
    // if (x != 2) {
    //     return;
    // }
    // x = visit(1);
    // if (x != 0) {
    //     return;
    // }
    // x = visit(3);
    // if (x != 2) {
    //     return;
    // }
    // x = visit(2);
    // if (x != 2) {
    //     return;
    // }
    // return;
}

Compilation message (stderr)

interface.cpp: In function 'int main()':
interface.cpp:44:55: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   44 |     if(fread(T.data(), sizeof(int), 2 * N - 2, stdin) != 2 * N - 2) exit(0);
      |        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
interface.cpp:50:33: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   50 |         int l = (numbers.size() == N ? N : 0);
      |                  ~~~~~~~~~~~~~~~^~~~

• Subtask 0: 0 / 0
• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40