Submission #577408

#	Time	Username	Problem	Language	Result	Execution time	Memory
577408		Theo830	The Big Prize (IOI17_prize)	C++17	20 / 100	89 ms	336 KiB

prize

#include <bits/stdc++.h>
using namespace std;
typedef int ll;
const ll INF = 1e9+7;
const ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<ll,ii>
#define ull unsigned int
#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
//int find_best(int n);
//std::vector<int> ask(int i);
#include "prize.h"
ll maxi = 0;
ll posa = 50;
ll solve(ll l,ll r,ll L,ll R){
    if(l > r){
        return -1;
    }
    ll mid = (l+r)/2;
    vector<int>res = ask(mid);
    posa++;
    if(res[0] == 0 && res[1] == 0){
        return mid;
    }
    if(l == r){
        return -1;
    }
    ll ans = -1;
    ll pos = mid;
    while(pos < r && (res[0] + res[1]) < maxi){
        pos++;
        res = ask(pos);
        posa++;
        while(posa >= 7000){

        }
        if(res[0] == 0 && res[1] == 0){
            return pos;
        }
    }
    if(res[0] + res[1] < maxi){
        pos = mid - 1;
        res = ask(mid);
        posa++;
        if(res[0] == 0 && res[1] == 0){
            return pos;
        }
        while(pos > l && (res[0] + res[1]) < maxi){
            pos--;
            res = ask(pos);
            posa++;
            while(posa >= 7000){

            }
            if(res[0] == 0 && res[1] == 0){
                return pos;
            }
        }
    }
    while(posa >= 7000){

    }
    if((res[0] + res[1]) == maxi){
        if(res[0] - L > res[1] - R){
            ans = solve(l,mid,L,R + res[1]);
            if(ans == -1){
                ans = solve(mid+1,r,L + res[0],R);
            }
        }
        else{
            ans = solve(mid+1,r,L + res[0],R);
            if(ans == -1){
                ans = solve(l,mid,L,R + res[1]);
            }
        }
    }
    return ans;
}
int find_best(int n){
    srand(time(0));
    ll k = 50;
    while(k--){
        vector<int> res = ask(rand() % n);
        maxi = max(maxi,res[0] + res[1]);
    }
    return solve(0,n-1,0,0);
}
/*
static const int max_q = 10000;
static int n;
static int query_count = 0;
static vector<int> g;
static vector<vector<int> > rank_count;

vector<int> ask(int i) {
    query_count++;
    if(query_count > max_q) {
        cerr << "Query limit exceeded" << endl;
        exit(0);
    }

    if(i < 0 || i >= n) {
        cerr << "Bad index: " << i << endl;
        exit(0);
    }

    vector<int> res(2);
    res[0] = rank_count[g[i] - 1][i + 1];
    res[1] = rank_count[g[i] - 1][n] - res[0];
    return res;
}

int main() {
    cin >> n;

    g.resize(n);
    for(int i = 0; i < n; i++) {
        cin >> g[i];
        if(g[i] < 1) {
            cerr << "Invalid rank " << g[i] << " at index " << i << endl;
            exit(0);
        }
    }

    int max_rank = *max_element(g.begin(), g.end());

    rank_count.resize(max_rank + 1, vector<int>(n + 1, 0));
    for(int r = 0; r <= max_rank; r++) {
        for(int i = 1; i <= n; i++) {
            rank_count[r][i] = rank_count[r][i - 1];
            if(g[i - 1] == r)
              rank_count[r][i]++;
        }
    }

    for(int i = 0; i <= n; i++)
        for(int r = 1; r <= max_rank; r++)
            rank_count[r][i] += rank_count[r - 1][i];

    int res = find_best(n);
    cout << res << endl << "Query count: " << query_count << endl;

    return 0;
}


8
3 2 3 3 3 3 2 1
*/

• Subtask 1: 20 / 20
• Subtask 2: 0 / 80