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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#613520 | #8239. Mysterious Tree | mojimoon | WA | 1ms | 3880kb | C++14 | 2.1kb | 2024-10-05 14:09:01 | 2024-10-05 14:12:05 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
/*
interactive problem
judge if the tree is a star or a chain
a star has 1 node with degree n-1 and the rest with degree 1
a chain has 2 nodes with degree 1 and the rest with degree 2
max number of queries allowed is n/2+4
*/
int main() {
int t;
scanf("%d", &t);
while (t--) {
int n;
scanf("%d", &n);
int u = -1, v = -1, r;
for (int i = 1; i < n; i+= 2) {
printf("? %d %d\n", i, i + 1);
fflush(stdout);
scanf("%d", &r);
if (r == 1) {
u = i;
v = i + 1;
break;
}
}
if (u == -1) {
if (n & 2) {
printf("? %d %d\n", n - 1, n);
fflush(stdout);
scanf("%d", &r);
if (r) {
u = n - 1;
v = n;
goto NXT;
}
}
printf("! 1\n"); // chain
fflush(stdout);
continue;
}
NXT:
int p1 = -1, p2 = -1;
// choose 2 arbitrary nodes other than u and v
for (int i = 1; i <= n; i++) {
if (i != u && i != v) {
if (p1 == -1) {
p1 = i;
} else {
p2 = i;
break;
}
}
}
printf("? %d %d\n", p1, u);
fflush(stdout);
scanf("%d", &r);
if (!r) {
printf("? %d %d\n", p1, v);
if (r) {
swap(u, v);
} else {
printf("! 1\n"); // chain
fflush(stdout);
continue;
}
}
if (r) {
printf("? %d %d\n", p2, u);
fflush(stdout);
scanf("%d", &r);
if (r) {
printf("! 2\n"); // star
fflush(stdout);
} else {
printf("! 1\n"); // chain
fflush(stdout);
}
}
}
}
Details
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Test #1:
score: 0
Wrong Answer
time: 1ms
memory: 3880kb
input:
2 4 1 0 1 4
output:
? 1 2 ? 3 1 ? 3 2 ! 1 ! 1
result:
wrong answer Wrong prediction (test case 2)