Submission #584583

#	Time	Username	Problem	Language	Result	Execution time	Memory
584583		Dan4Life	Aliens (IOI07_aliens)	C++17	0 / 100	2 ms	300 KiB

aliens

#include <bits/stdc++.h>
using namespace std;
#define int long long
using ll = 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){
    ll d = 1; 
	while(query(x + dx * d, y + dy * d)) d <<= 1; 
	ll lo = d >> 1, hi = d, idx; 
	while(lo <= hi) {
		ll mid = lo + hi >> 1; 
		if(query(x + dx * mid, y + dy * mid))
			lo = mid + 1, idx = mid; 
		else hi = mid - 1; 
	} return idx;
}

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 = r+l/2, by = u+d/2;
    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, ansy = by+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:21:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   21 |   ll mid = lo + hi >> 1;
      |            ~~~^~~~
aliens.cpp:25:11: warning: 'idx' may be used uninitialized in this function [-Wmaybe-uninitialized]
   25 |  } return idx;
      |           ^~~

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