Submission #293147

#	Time	Username	Problem	Language	Result	Execution time	Memory
293147		Saboon	The Big Prize (IOI17_prize)	C++17	95.64 / 100	85 ms	7344 KiB

prize

#include "prize.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
 
int Max = 0;
const int maxn = 2e5 + 10;
vector<int> Q[maxn];
bool mark[maxn];
 
vector<int> Ask(int i){
    if (mark[i])
        return Q[i];
    mark[i] = 1;
    return Q[i] = ask(i);
}
 
int solve(int l, int r, int cnt, int pre = 0, int suf = 0){
    if (cnt <= 0 or l >= r)
        return -1;
    if (l+1 == r){
        vector<int> res = Ask(l);
        if (res[0]+res[1] == 0)
            return l;
        return -1;
    }
    vector<int> Vals;
    int m = (l+r)>>1;
    Vals.push_back(m);
    for (int i = 1; ;i++){
        bool found = 0;
        if (m+i < r)
            found = 1, Vals.push_back(m+i);
        if (m-i >= l)
            found = 1, Vals.push_back(m-i);
        if (!found)
            break;
    }
    int Mn = m, Mx = m;
    for (auto mid : Vals){
        Mn = min(Mn, mid);
        Mx = max(Mx, mid);
        vector<int> res = Ask(mid);
        if (res[0]+res[1] == 0)
            return mid;
        if (res[0]+res[1] == Max){
            int ret = solve(l,Mn,res[0]-pre, pre, res[1]);
            if (ret != -1)
                return ret;
            return solve(Mx+1, r, res[1]-suf, res[0], suf);
        }
    }
    return -1;
}
 
int find_best(int n){
    for (int i = 0; i < min(n,500); i++){
        vector<int> res = Ask(i);
        Max = max(Max, res[0]+res[1]);
        if (Max >= 500)
            break;
    }
    return solve(0, n, Max);
}

• Subtask 1: 20 / 20
• Subtask 2: 75.64 / 80