Submission #506028

#	Time	Username	Problem	Language	Result	Execution time	Memory
506028		LouayFarah	Combo (IOI18_combo)	C++14	30 / 100	56 ms	540 KiB

combo

#include "bits/stdc++.h"

using namespace std;

#define endl "\n"
#define ll long long int
#define pb push_back
#define mp make_pair
#define fi first
#define se second

const long long MOD = 1e9+7;
const long long INF = 1e18;

int nx[4] = {0, 0, -1, 1};
int ny[4] = {1, -1, 0, 0};

ll my_rand(ll l, ll r)
{
    srand(chrono::steady_clock::now().time_since_epoch().count());

    ll len = r-l;
    ll a = rand()%len;
    ll b = rand()%len;

    ll res = ((((a%len)*((RAND_MAX+1)%len))%len) + (b%len))%len;

    if(res<l)
        res +=l;

    return res;
}

int press(string p);

string guess_sequence(int n)
{
    string s = "";
    string choices = "ABXY";

    string p = "";
    vector<bool> visited(4, false);
    ll restricted = 0;
    while(true)
    {
        ll x = my_rand(0, 4);
        if(visited[x])
            continue;
        visited[x] = true;
        p.pb(choices[x]);
        if(press(p)==1)
        {
            s = p;
            restricted = x;
            break;
        }
        p = s;
    }


    while(int(s.length())<n)
    {
        vector<bool> used(4, false);
        used[restricted] = true;
        p = s;

        while(true)
        {
            p = s;
            ll x = my_rand(0, 4);
            if(used[x])
                continue;

            ll cnt_not_used = 0;
            char c;
            for(int i = 0; i<4; i++)
            {
                if(!used[i])
                {
                    cnt_not_used++;
                    c = choices[i];
                }
            }

            if(cnt_not_used==1)
            {
                s.pb(c);
                break;
            }
            else
            {
                p.pb(choices[x]);
                used[x] = true;
                if(press(p)==int(s.length())+1)
                {
                    s.pb(choices[x]);
                    break;
                }
            }
        }
    }

    return s;
}

Compilation message (stderr)

combo.cpp: In function 'long long int my_rand(long long int, long long int)':
combo.cpp:26:35: warning: integer overflow in expression of type 'int' results in '-2147483648' [-Woverflow]
   26 |     ll res = ((((a%len)*((RAND_MAX+1)%len))%len) + (b%len))%len;
      |                                   ^

• Subtask 1: 5 / 5
• Subtask 2: 25 / 95