Submission #414435

#	Time	Username	Problem	Language	Result	Execution time	Memory
414435		Theo830	Counting Mushrooms (IOI20_mushrooms)	C++17	80.71 / 100	11 ms	452 KiB

mushrooms

#include <bits/stdc++.h>
using namespace std;
typedef int ll;
ll INF = 1e9+7;
ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<ll,ii>
#define f(i,a,b) for(ll i = a;i < b;i++)
#define pb push_back
#define vll vector<ll>
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
///I hope I will get uprating and don't make mistakes
///I will never stop programming
///sqrt(-1) Love C++
///Please don't hack me
///@TheofanisOrfanou Theo830
///Think different approaches (bs,dp,greedy,graphs,shortest paths,mst)
///Stay Calm
///Look for special cases
///Beware of overflow and array bounds
///Think the problem backwards
///Training
#include "mushrooms.h"
/*
int count_mushrooms(int n);
int use_machine(std::vector<int> x);
static char fmt_buffer[100000];
#define FMT_TO_STR(fmt, result) va_list vargs; va_start(vargs, fmt); \
	vsnprintf(fmt_buffer, sizeof(fmt_buffer), fmt, vargs); \
	va_end(vargs); fmt_buffer[sizeof(fmt_buffer)-1] = 0; \
	std::string result(fmt_buffer);

static const int min_n = 2;
static const int max_n = 20000;
static const int max_qc = 20000;
static const int max_qs = 100000;
static const int species_A = 0;
static const int species_B = 1;

static int n;
static std::vector<int> species;
static int qc, qs;

static inline void error_if(bool cond, std::string message) {
	if (cond) {
		printf("%s\n", message.c_str());
		exit(0);
	}
}

static inline void wrong_if(bool cond, std::string message) {
	error_if(cond, "Wrong Answer: "+message);
}

int use_machine(std::vector<int> x) {
	const int xs = x.size();
	wrong_if(xs < 2, "Too small array for query.");
	wrong_if(xs > n, "Too large array for query.");
	qc++;
	wrong_if(qc > max_qc, "Too many queries.");
	qs += xs;
	wrong_if(qs > max_qs, "Too many total array sizes as queries.");
	for (int i = 0; i < xs; i++)
		wrong_if(x[i] < 0 || n - 1 < x[i], "Invalid value in the query array.");
	std::vector<bool> used(n, false);
	for (int i = 0; i < xs; i++) {
		wrong_if(used[x[i]], "Duplicate value in the query array.");
		used[x[i]] = true;
	}
	int diffs = 0;
	for (int i = 1; i < xs; i++)
		diffs += int(species[x[i]] != species[x[i-1]]);
	return diffs;
}

#ifdef __GNUC__
__attribute__ ((format(printf, 2, 3)))
#endif
static inline void check_input(bool cond, const char* message_fmt, ...) {
	FMT_TO_STR(message_fmt, message);
	error_if(!cond, "Invalid input: "+message);
}

int main() {
	check_input(1 == scanf("%d", &n), "Could not read n.");
	check_input(min_n <= n, "n must not be less than %d, but it is %d.", min_n, n);
	check_input(n <= max_n, "n must not be greater than %d, but it is %d.", max_n, n);
	species.resize(n);
	for (int i = 0; i < n; i++) {
		check_input(1 == scanf("%d", &species[i]), "Could not read species element [%d].", i);
		check_input(species[i]==species_A || species[i] == species_B,
					"Species elements must be %d or %d, but species element [%d] is %d.", species_A, species_B, i, species[i]);
	}
	check_input(species[0] == species_A, "Species element [%d] must be %d.", 0, species_A);
	// Postponed closing standard input in order to allow interactive usage of the grader.

	qc = 0;
	qs = 0;
	int answer = count_mushrooms(n);
	printf("%d\n%d\n", answer, qc);
	fclose(stdout);
	fclose(stdin);
	return 0;
}
*/
int count_mushrooms(int n){
    ll ans = 0;
    vll a,b;
    a.pb(0);
    ll pos = 1;
    ll v = 50;
    while(pos < n && max(a.size(),b.size()) < v){
        vll c;
        if(pos+1 == n || max(a.size(),b.size()) == 1){
            c.pb(pos);
            c.pb(0);
            if(use_machine(c) == 1){
                b.pb(pos);
            }
            else{
                a.pb(pos);
            }
          	pos++;
            break;
        }
        vll e = a;
        if(b.size() > a.size()){
            e = b;
        }
        c.pb(e[0]);
        c.pb(pos);
        c.pb(e[1]);
        c.pb(pos+1);
        ll p = use_machine(c);
        if(p % 2 == 1){
            if(e[0] == 0){
                b.pb(pos+1);
            }
            else{
                a.pb(pos+1);
            }
        }
        else{
            if(e[0] == 0){
                a.pb(pos+1);
            }
            else{
                b.pb(pos+1);
            }
        }
        if((p/2) == 1){
            if(e[0] == 0){
                b.pb(pos);
            }
            else{
                a.pb(pos);
            }
        }
        else{
            if(e[0] == 0){
                a.pb(pos);
            }
            else{
                b.pb(pos);
            }
        }
        pos += 2;
    }
    ans = a.size();
    ll p;
    f(i,pos,n){
        vll c;
        if(a.size() > b.size()){
            ll posa = 0;
            for(auto x:a){
                if(i == n){
                   break;
                }
                c.pb(x);
                c.pb(i);
                posa++;
                i++;
            }
            p = use_machine(c);
            if(p % 2 == 0){
                a.pb(i-1);
            }
            else{
                b.pb(i-1);
            }
            ans += (c.size() - posa - ((p + 1) / 2));
        }
        else{
            for(auto x:b){
                if(i == n){
                   break;
                }
                c.pb(x);
                c.pb(i);
                i++;
            }
            p = use_machine(c);
            if(p % 2 == 0){
                b.pb(i-1);
            }
            else{
                a.pb(i-1);
            }
            ans += (p + 1) / 2;
        }
        i--;
    }
	return ans;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int count_mushrooms(int)':
mushrooms.cpp:114:45: warning: comparison of integer expressions of different signedness: 'const long unsigned int' and 'll' {aka 'int'} [-Wsign-compare]
  114 |     while(pos < n && max(a.size(),b.size()) < v){
      |                      ~~~~~~~~~~~~~~~~~~~~~~~^~~

• Subtask 1: 80.7143 / 100