Submission #289317

#	Time	Username	Problem	Language	Result	Execution time	Memory
289317		zecookiez	Aliens (IOI07_aliens)	C++17	100 / 100	2 ms	512 KiB

aliens

#include <bits/stdc++.h>
using namespace std;
template<class C>constexpr int len(const C&c){return int(c.size());}

const int DDX[13] = {-2, 0, 2, -1, 1, -2, 0, 2, -1, 1, -2, 0, 2};
const int DDY[13] = {-2, -2, -2, -1, -1, 0, 0, 0, 1, 1, 2, 2, 2};
long long N;

bool rng(long long X){
    return 1 <= X && X <= N;
}

map<pair<long long, long long>, bool> memo;
bool query(long long X, long long Y){
    if(!rng(X) || !rng(Y)) return false;
    if(memo.count(make_pair(X, Y))) return memo[make_pair(X, Y)];
    cout << "examine " << X << " " << Y << endl;
    string s; cin >> s;
    return memo[make_pair(X, Y)] = (s == "true");
}

int main(){
    cin.sync_with_stdio(0); cin.tie(0); cout.tie(0);
    long long XS, YS, X1, Y1, X2, SZ, XC, YC, i = 1; cin >> N >> XS >> YS;
    // find offset from center of current square
    // find right side
    for(X1 = XS; ; i += i){
        if(!query(X1 + i, YS)){
            X1 += i / 2LL; break;
        }
    }
    long long L = X1, R = X1 + i / 2LL, MID;
    while(R - L > 1){
        MID = L + (R - L) / 2;
        if(query(MID, YS)) L = MID;
        else R = MID;
    }
    // find left side
    X1 = L; X2 = XS;
    for(i = 1; ; i += i){
        if(!query(X2 - i, YS)){
            X2 -= i / 2LL; break;
        }
    }
    L = X2 - i / 2LL; R = X2;
    while(R - L > 1){
        MID = L + (R - L) / 2;
        if(query(MID, YS)) R = MID;
        else L = MID;
    }
    // find top side
    X2 = R; SZ = X1 - X2 + 1; XC = (X1 + X2) / 2; Y1 = YS;
    for(i = 1; ; i += i){
        if(!query(XC, Y1 - i)){
            Y1 -= i / 2LL; break;
        }
    }
    L = Y1 - i / 2LL; R = Y1;
    while(R - L > 1){
        MID = L + (R - L) / 2;
        if(query(XC, MID)) R = MID;
        else L = MID;
    }
    // bottom side
    Y1 = R; YC = Y1 + SZ / 2;
    // +41 queries for finding center
    for(int i = 0; i < 13; ++i){
        X1 = XC + SZ * DDX[i];
        Y1 = YC + SZ * DDY[i];
        if(!rng(X1) || !rng(Y1)) continue;
        int cnt = 0;
        for(int j = 0; j < 13; ++j){
            XS = X1 + SZ * DDX[j];
            YS = Y1 + SZ * DDY[j];
            if(rng(XS) && rng(YS) && query(XS, YS)) ++cnt;
            else break;
        }
        if(cnt == 13){
            cout << "solution " << X1 << " " << Y1 << endl;
            return 0;
        }
    }
    return 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