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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#884010 | #9734. Identify Chord | Estelle_N | WA | 2ms | 1664kb | C++14 | 1.9kb | 2025-02-05 20:49:17 | 2025-02-05 20:49:18 |
Judging History
answer
#include <cstdio>
#include <algorithm>
using namespace std;
int T, n;
int ask(int x, int y, int z = 0)
{
printf("? %d %d\n", x, y);
fflush(stdout);
scanf("%d", &z);
return z;
}
void ans(int x, int y, int z = 0)
{
printf("! %d %d\n", x, y);
fflush(stdout);
scanf("%d", &z);
}
int dis(int x, int y)
{
if(x > y)
swap(x, y);
return min(y - x, x + n - y);
}
void work()
{
scanf("%d", &n);
if(n <= 8)
{
for(int i = 1; i <= n; ++ i)
for(int j = i + 2; j <= n; ++ j)
if(!(i == 1 && j == n) && ask(i, j) == 1)
return ans(i, j);
}
int u = 1, v = n / 2 + 1, w = n / 2, d = ask(u, v);
while(d == w)
{
if(n & 1)
{
if(w == n / 2)
++ v, ++ w;
else
++ u, -- w;
}
else
++ u, ++ v;
d = ask(u, v);
}
if(d == 1)
return ans(u, v);
int delta = w - d;
int x = u + 1, y = v, z = dis(x, y), k = ask(x, y);
if(k == 1)
return ans(x, y);
if(z - k == delta)
u = x, v = y, w = z, d = k;
else
{
(-- u == 0) && (u = n);
if(u > v)
swap(u, v);
w = dis(u, v), d = w - delta;
if(d == 1)
return ans(u, v);
}
int l = u, r = v - delta - 1;
while(l <= r)
{
int mid = l + r >> 1;
if(dis(mid, v) - ask(mid, v) == delta)
l = mid + 1, x = mid;
else
r = mid - 1;
}
y = (x + delta + 1) % n;
if(!y)
y = n;
if(ask(x, y) != 1)
{
y = ((x - delta - 1) % n + n) % n;
if(!y)
y = n;
}
ans(x, y);
}
int main()
{
scanf("%d", &T);
while(T --)
work();
return 0;
}
Details
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Test #1:
score: 100
Accepted
time: 0ms
memory: 1664kb
input:
2 6 2 2 2 1 1 4 1 1
output:
? 1 3 ? 1 4 ? 1 5 ? 2 4 ! 2 4 ? 1 3 ! 1 3
result:
ok ok (2 test cases)
Test #2:
score: -100
Wrong Answer
time: 2ms
memory: 1664kb
input:
1000 15 5 4 3 2 1 1 1 19 5 4 3 4 5 -1
output:
? 1 8 ? 2 8 ? 3 8 ? 4 8 ? 5 8 ? 5 8 ! 5 8 ? 1 10 ? 2 10 ? 3 10 ? 4 10 ? 3 8 ! 3 17
result:
wrong answer Wrong answer n=19, actual=3-12, guessed=3-17 (test case 2)