Submission #584576

#	Time	Username	Problem	Language	Result	Execution time	Memory
584576		Dan4Life	Aliens (IOI07_aliens)	C++17	0 / 100	3 ms	208 KiB

aliens

#include <bits/stdc++.h>
using namespace std;
#define int long long
int n, m, l, r, u, d, X, Y, bx, by;
map<pair<int,int>,bool> M;

bool query(int x, int y){
    if(x<1 or y<1 or x>n or y>n) return 0;
    if(M.count({x,y})) return M[{x,y}];
    cout << "examine " << x << " " << y << endl;
    string s; cin >> s;
    return M[{x,y}]=(s=="true");
}

int binsearch(int x, int y, int dx, int dy){
    int en = 1; while(query(x+dx*en, y+dy*en)) en*=2;
    int l = en/2, r = en, ans;
    while(l<=r){
        int mid = (l+r)/2;
        if(query(x+dx*mid,y+dy*mid)) l=mid+1, ans = mid; 
        else r=mid-1;
    }
    return ans;
}

int32_t main()
{
    cin >> n >> X >> Y; M[{X,Y}]=1;
    l = X-binsearch(X,Y,-1,0);
    r = X+binsearch(X,Y,1,0);
    u = Y+binsearch(X,Y,0,1);
    m = r-l+1, d = u-m+1;
    int bx = X-l, by = Y-d;
    while(query(bx-m, by-m)) bx-=m, by-=m;
    while(query(bx, by-2*m)) by-=2*m;
    while(query(bx-2*m, by)) bx-=2*m;
    int ansx = bx+m*2+m/2, ansy = by+m*2+m/2; 
    cout << "solution " << ansx << " " << ansy << endl;
}

Compilation message (stderr)

aliens.cpp: In function 'long long int binsearch(long long int, long long int, long long int, long long int)':
aliens.cpp:23:12: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   23 |     return ans;
      |            ^~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10