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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#853696 | #9734. Identify Chord | ucup-team4435# | RE | 0ms | 0kb | C++20 | 7.9kb | 2025-01-11 18:21:02 | 2025-01-11 18:21:03 |
answer
//#pragma GCC optimize("Ofast")
#include "bits/stdc++.h"
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep1(i, n) for (int i = 1; i < (n); ++i)
#define rep1n(i, n) for (int i = 1; i <= (n); ++i)
#define repr(i, n) for (int i = (n) - 1; i >= 0; --i)
#define pb push_back
#define eb emplace_back
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define each(x, a) for (auto &x : a)
#define ar array
#define vec vector
#define range(i, n) rep(i, n)
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using str = string;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vpi = vector<pair<int, int>>;
using vvi = vector<vi>;
int Bit(int mask, int b) { return (mask >> b) & 1; }
template<class T>
bool ckmin(T &a, const T &b) {
if (b < a) {
a = b;
return true;
}
return false;
}
template<class T>
bool ckmax(T &a, const T &b) {
if (b > a) {
a = b;
return true;
}
return false;
}
// [l, r)
template<typename T, typename F>
T FindFirstTrue(T l, T r, const F &predicat) {
--l;
while (r - l > 1) {
T mid = l + (r - l) / 2;
if (predicat(mid)) {
r = mid;
} else {
l = mid;
}
}
return r;
}
template<typename T, typename F>
T FindLastFalse(T l, T r, const F &predicat) {
return FindFirstTrue(l, r, predicat) - 1;
}
const int INFi = 2e9;
const ll INF = 2e18;
const bool Loc = false;
int Dist(int x, int y, int n) {
int f = abs(x - y);
f = min(f, n - f);
return f;
}
void solve() {
int n = 1e9; cin >> n;
pair<int, int> hord;
if (Loc) {
// hord = {2, n - 1};
// cin >> hord.first >> hord.second;
}
map<pair<int, int>, int> mem;
vpi ans;
int qs = 0;
auto ask = [&] (int x, int y) {
if (x == y) return 0;
if ((x + 1) % n == y || (y + 1) % n == x) return 1;
x++;
y++;
if (Loc) {
qs++;
int dist = min({Dist(x, y, n), Dist(x, hord.first, n) + Dist(hord.second, y, n) + 1, Dist(x, hord.second, n) + Dist(hord.first, y, n) + 1});
if (dist == 1) {
ans.emplace_back(x, y);
}
return dist;
}
if (x > y) swap(x, y);
pi cur = make_pair(x, y);
if (mem.count(cur)) return mem[cur];
cout << "? " << x << ' ' << y << endl;
int ret; cin >> ret;
mem[cur] = ret;
if (ret == 1) {
ans.emplace_back(cur);
}
return ret;
};
{
ll cnt = 1ll * n * (n - 1) / 2;
cnt -= n;
if (cnt <= 40) {
for (int i = 2; i < n && ans.empty(); ++i) {
for (int j = 0; j + 2 <= i && ans.empty(); ++j) {
ask(j, i);
}
}
assert(!ans.empty());
cout << "! " << ans[0].first << ' ' << ans[0].second << endl;
return;
}
}
assert(n >= 10);
if (n % 2 == 0) {
int mid = n / 2;
for (int x = 0; x < n && ans.empty(); ++x) {
assert(x <= 2);
int y = (x + mid) % n;
int dist = ask(x, y);
if (dist == mid) continue;
if (!ans.empty()) break;
assert(dist < mid);
int len = mid - dist + 1;
assert(len >= 2);
ask((y + len) % n, y);
if (!ans.empty()) break;
ask((y - len + n) % n, y);
if (!ans.empty()) break;
if (ask(x, (y + 1) % n) == dist - 1) {
// down
if (!ans.empty()) break;
int L = 1;
int R = mid - len + 1;
while (R - L > 1 && ans.empty()) {
int M = (L + R) / 2;
if (ask(x, (y + M) % n) == dist - M) {
L = M;
} else {
R = M;
}
}
for(int t = -1; t <= 1 && ans.empty(); t += 2) {
int f1 = (y + L) % n;
int f2 = (y + 1ll * t * (L + len)) % n;
if (f2 < 0) f2 += n;
ask(f1, f2);
}
assert(!ans.empty());
} else {
if (!ans.empty()) break;
int L = 1;
int R = mid - len + 1;
while (R - L > 1 && ans.empty()) {
int M = (L + R) / 2;
if (ask(x, (y - M + n) % n) == dist - M) {
L = M;
} else {
R = M;
}
}
for(int t = -1; t <= 1 && ans.empty(); t += 2) {
int f1 = (y - L + n) % n;
int f2 = (y + 1ll * t * (L + len)) % n;
if (f2 < 0) f2 += n;
ask(f1, f2);
}
assert(!ans.empty());
}
break;
}
} else {
int mid = n / 2;
for (int x = 0; x < n && ans.empty(); ++x) {
assert(x <= 2);
int y1 = (x + mid) % n;
int y2 = (x + mid + 1) % n;
int dist1 = ask(x, y1);
if (!ans.empty()) break;
int dist2 = ask(x, y2);
if (!ans.empty()) break;
if (dist1 == dist2) {
assert(dist1 == mid);
continue;
}
int len = mid - min(dist1, dist2) + 1;
assert(len >= 2);
if (dist1 < dist2) {
int L = 0;
int R = mid - len + 1;
while (R - L > 1 && ans.empty()) {
int M = (L + R) / 2;
if (ask(x, (y1 - M + n) % n) == dist1 - M) {
L = M;
} else {
R = M;
}
}
if (ans.empty()) {
int f1 = (y1 - L + n) % n;
int f2 = (y1 - (L + len)) % n;
if (f2 < 0) f2 += n;
ask(f1, f2);
}
if (ans.empty()) {
int f1 = (y1 - L + n) % n;
int f2 = (y2 + (L + len)) % n;
if (f2 < 0) f2 += n;
ask(f1, f2);
}
assert(!ans.empty());
} else {
int L = 0;
int R = mid - len + 1;
while (R - L > 1 && ans.empty()) {
int M = (L + R) / 2;
if (ask(x, (y2 + M) % n) == dist2 - M) {
L = M;
} else {
R = M;
}
}
if (ans.empty()) {
int f1 = (y2 + L) % n;
int f2 = (y1 - (L + len)) % n;
if (f2 < 0) f2 += n;
ask(f1, f2);
}
if (ans.empty()) {
int f1 = (y2 + L) % n;
int f2 = (y2 + (L + len)) % n;
if (f2 < 0) f2 += n;
ask(f1, f2);
}
assert(!ans.empty());
}
break;
}
}
assert(!ans.empty());
cout << "! " << ans[0].first << ' ' << ans[0].second << endl;
int ret; cin >> ret;
if (ret == -1) {
exit(0);
}
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout << setprecision(12) << fixed;
int t = 1;
cin >> t;
rep(i, t) {
solve();
}
return 0;
}
Details
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Test #1:
score: 0
Runtime Error
input:
2 6 2 2 1 1 4
output:
? 1 3 ? 1 4 ? 2 4 ! 2 4