Submission #430399

#	Time	Username	Problem	Language	Result	Execution time	Memory
430399		Dremix10	The Big Prize (IOI17_prize)	C++17	90 / 100	144 ms	7744 KiB

prize

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pi;
typedef pair<ll,ll> pl;
#define endl '\n'
#define F first
#define S second
#define all(x) (x).begin(),(x).end()
const int N = 3e5+1;
const ll INF = 2e18;
const int MOD = 1e9+7;

vector<int> ask(int i);

vector<vector<int> > memo(N);

const int block = 5;
int nn;
int queried = 0;

vector<int> askme(int i){
    if(memo[i].empty()){
        queried++;
        assert(queried <= 10000);
        memo[i] = ask(i);
    }
    return memo[i];
}

int seen,cheap;

int go(int b){
    for(int i=b*block;i<min(nn,(b+1)*block);i++){
        vector<int> arr = askme(i);
        if(arr[0] + arr[1] == 0)
            return i;
        if(arr[0] + arr[1] < cheap)
            seen++;
    }
    return -1;
}

int find_best(int n) {
    /// the second to smallest price is in at most 450 boxes
    /// the maximum amount of prizes is 5

    nn = n;
    int blocks = (n+4)/5;

    for(int i=0;i<min(1000,n);i++){
        vector<int> arr = askme(i);
        cheap = max(cheap,arr[0] + arr[1]);
    }
    int L = 0,R = blocks-2;

    while(L<=R){
        int l = L,r = R;
        int target = -1;
        while(l<=r){
            int mid = (l+r)/2;
            int low,high,pos;

            pos = (mid+1)*block;
            vector<int> arr = askme(pos);
            low = arr[0],high = arr[1];
            if(low + high == 0)
                return pos;
            if(low + high < cheap){
                bool chk = 0;
                arr = askme(pos-1);
                if(arr[0] + arr[1] < cheap || arr[0] - seen > 0)
                    chk = 1;
                if(arr[0] + arr[1] == 0)
                    return pos-1;
                if(chk){
                    target = mid;
                    r = mid-1;
                }
                else{
                    target = mid+1;
                    break;
                }
                continue;
            }
            if(low - seen > 0){
                target = mid;
                r = mid-1;
            }
            else
                l = mid+1;
        }
        if(target == -1)
            target = blocks-1;
        int ans = go(target);
        if(ans != -1)
            return ans;
        L = target+1;
    }
    int ans = go(blocks-1);
    if(ans != -1)
        return ans;
    assert(0);
    return 0;

}

• Subtask 1: 20 / 20
• Subtask 2: 70 / 80