Submission #307097

#	Time	Username	Problem	Language	Result	Execution time	Memory
307097		phathnv	Finding Routers (IOI20_routers)	C++14	100 / 100	2 ms	768 KiB

routers

#include "routers.h"
#include <bits/stdc++.h>

using namespace std;

int asked[200001];
int ask(int x){
    if (asked[x] != -1)
        return asked[x];
    asked[x] = use_detector(x);
    return asked[x];
}

vector <int> find_routers(int l, int n, int q){
    vector <int> res;
    res.push_back(0);
    int cur = 0;
    for(int i = 0; i <= l; i++)
        asked[i] = -1;

    if (n == 2){
        int mid = 1;
        for(int j = 16; j >= 0; j--){
            if (mid + (1 << j) > l)
                continue;
            if (ask(mid + (1 << j)) == 0)
                mid += (1 << j);
        }
        res.push_back(2 * mid);
        return res;
    }

    for(int i = 1; i < n; i++){
        int mid = cur + 1;
        while (ask(min(l, mid + 64)) == i - 1)
            mid = min(l, mid + 64);

        for(int j = 5; j >= 0; j--){
            if (mid + (1 << j) > l)
                continue;
            if (ask(mid + (1 << j)) == i - 1)
                mid += (1 << j);
        }
        int nxt = 2 * mid - cur;
        res.push_back(nxt);
        cur = nxt;
    }
    return res;
}

• Subtask 1: 16 / 16
• Subtask 2: 21 / 21
• Subtask 3: 23 / 23
• Subtask 4: 40 / 40