Submission #679116

#	Time	Username	Problem	Language	Result	Execution time	Memory
679116		Hacv16	Aliens (IOI07_aliens)	C++17	100 / 100	4 ms	208 KiB

aliens

#include<bits/stdc++.h>
using namespace std;

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

#define int long long

int n, x, y, m, numblock, numq;
 
bool check(int x){ return x > 0 && x <= n ;}

bool query(int x, int y){
    if(!check(x) || !check(y)) return false;
    assert(++numq <= 300);
    cout << "examine " << x << ' ' << y << '\n'; fflush(stdout);
    string ans; cin >> ans; return (ans == "true");
}

pair<int, int> findCenter(int x, int y, int m){
    int l = 0, r = 2 * n / m, curx = x, cury = y, jump = 0;
 
    //Diagonal jump
    while(l <= r){
        int mid = (l + r) >> 1;
        int nx = curx + m * mid, ny = cury + m * mid;
        if(query(nx, ny)) l = mid + 1, jump = mid;
        else r = mid - 1;
    }   
 
    curx += jump * m;
    cury += jump * m;
 
    l = 0, r = ((n + m - 1) / m), jump = 0;
 
    //Upwards jump
    while(l <= r){
        int mid = (l + r) >> 1;
        int ny = cury + m * (2 * mid);
        if(query(curx, ny)) l = mid + 1, jump = 2 * mid;
        else r = mid - 1;
    }
 
    cury += jump * m;
 
    //Left jump
    l = 0, r = ((n + m - 1)/ m), jump = 0;
 
    while(l <= r){
        int mid = (l + r) >> 1;
        int nx = curx - m * (2 * mid);
        if(query(nx, cury)) l = mid + 1, jump = 2 * mid;
        else r = mid - 1;
    }
 
    curx -= jump * m;
    
    //move to center of current block
    curx += (m - 1) / 2;
    cury -= (m - 1) / 2;
    
    //move to center block
    l = 0, r = ((n + m - 1) / m), jump = 0;
 
    while(l <= r){
        int mid = (l + r) >> 1;
        int nx = curx + m * (2 * mid);
        if(query(nx, cury)) l = mid + 1, jump = 2 * mid;
        else r = mid - 1;
    }
 
    numblock = jump + 1;
 
    curx += ((numblock - 1) / 2) * m;
    cury -= ((numblock - 1) / 2) * m;
    
    return {curx, cury};
}

pair<int, int> getPos(int x, int y, int dx, int dy){
    int pw = 0;

    for(int i = 0; i < 31; i++)
        if(!query(x + dx * (1 << i), y + dy * (1 << i))){ pw = i; break; }

    if(dx == 0 && dy == 1){
        int l = y, r = min(n, y + (1 << pw));

        while(l <= r){
            int mid = (l + r) >> 1;
            if(query(x, mid)) l = mid + 1;
            else r = mid - 1;
        }

        return {x, max(y, l - 1)};

    }else if(dx == 0 && dy == -1){
        int l = max(1LL, y - (1 << pw)), r = y;

        while(l <= r){
            int mid = (l + r) >> 1;
            if(query(x, mid)) r = mid - 1;
            else l = mid + 1;
        }

        return {x, min(y, r + 1)};

    }else{
        int l = max(1LL, x - (1 << pw)), r = x;

        while(l <= r){
            int mid = (l + r) >> 1;
            if(query(mid, y)) r = mid - 1;
            else l = mid + 1;
        }
        return {min(x, r + 1), y};
    }

    return {x, y};
}
 
int32_t main(){
    cin >> n >> x >> y;

    pair<int, int> top = getPos(x, y, 0, 1);
    pair<int, int> bot = getPos(x, y, 0, -1);
    pair<int, int> lef = getPos(x, y, -1, 0);

    int m = top.second - bot.second + 1, cury = top.second, curx = lef.first;

    pair<int, int> resp = findCenter(curx, cury, m);

    cout << "solution " << resp.first << ' ' << resp.second << '\n';

    exit(0);
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10