Submission #765846

#	Time	Username	Problem	Language	Result	Execution time	Memory
765846		GrindMachine	Easter Eggs (info1cup17_eastereggs)	C++17	100 / 100	21 ms	360 KiB

eastereggs

// Om Namah Shivaya

#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) 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(x) 42
#endif

/*

knew beforehand that this problem could be solved using b.s + querying something on pref
but the idea was not so hard to figure out on my own

*/

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

#include "grader.h"

int findEgg(int n, vector<pii> edges){
    vector<int> adj[n+5];
    for(auto [u,v] : edges){
        adj[u].pb(v), adj[v].pb(u);
    }

    queue<int> q;
    vector<bool> vis(n+5);
    vector<int> order;

    q.push(1);
    vis[1] = 1;

    while(!q.empty()){
        int u = q.front();
        q.pop();
        order.pb(u);

        trav(v,adj[u]){
            if(vis[v]) conts;
            q.push(v);
            vis[v] = 1;
        }
    }

    int l = 0, r = n-2;
    int first = n-1;

    while(l <= r){
        int mid = (l+r) >> 1;
        vector<int> ask;
        rep(i,mid+1) ask.pb(order[i]);

        if(query(ask)){
            first = mid;
            r = mid-1;
        }
        else{
            l = mid+1;
        }
    }

    int ans = order[first];
    return ans;
}

• Subtask 1: 40 / 40
• Subtask 2: 40 / 40
• Subtask 3: 20 / 20