#include <stdio.h>
#define N 3000000
int main() {
int t;
scanf("%d", &t);
while (t--) {
static int aa[N], uu[N * 2], vv[N * 2];
static char flipped[N];
int n, cnt, h, i, j, p, good, tmp;
scanf("%d", &n), n /= 2;
for (i = 0; i < n * 2; i++)
scanf("%d", &aa[i]), aa[i]--;
good = 1;
for (i = 0; i < n; i++)
if (aa[i] + aa[n * 2 - 1 - i] != n * 2 - 1) {
good = 0;
break;
}
if (!good) {
printf("-1\n");
continue;
}
good = 1;
for (i = 0; i < n; i++)
if ((flipped[i] = aa[i] > aa[n * 2 - 1 - i])) {
good ^= 1;
aa[i] = aa[n * 2 - 1 - i];
}
if (!good) {
printf("-1\n");
continue;
}
cnt = 0;
for (i = 0, p = -1; i < n; i++) {
while ((j = aa[i]) != i) {
tmp = aa[i], aa[i] = aa[j], aa[j] = tmp;
if (!flipped[i])
uu[cnt] = i, vv[cnt] = j, cnt++;
else
uu[cnt] = i, vv[cnt] = n * 2 - 1 - j, cnt++;
flipped[i] ^= flipped[j], flipped[j] = 0;
}
if (flipped[i]) {
if (p == -1)
p = i;
else {
uu[cnt] = i, vv[cnt] = p, cnt++;
uu[cnt] = i, vv[cnt] = n * 2 - 1 - p, cnt++;
p = -1;
}
}
}
printf("%d %d\n", cnt, cnt);
for (h = 0; h < cnt; h++)
printf("%d %d\n", uu[h] + 1, vv[h] + 1);
}
return 0;
}
Compilation message
cat.c: In function 'main':
cat.c:8:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
8 | scanf("%d", &t);
| ^~~~~~~~~~~~~~~
cat.c:14:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
14 | scanf("%d", &n), n /= 2;
| ^~~~~~~~~~~~~~~
cat.c:16:4: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
16 | scanf("%d", &aa[i]), aa[i]--;
| ^~~~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
4 ms |
6492 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
17 ms |
6748 KB |
Output is correct |
2 |
Correct |
17 ms |
6744 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
4 ms |
6492 KB |
Output is correct |
2 |
Correct |
17 ms |
6748 KB |
Output is correct |
3 |
Correct |
17 ms |
6744 KB |
Output is correct |
4 |
Correct |
19 ms |
6748 KB |
Output is correct |
5 |
Correct |
8 ms |
6612 KB |
Output is correct |
6 |
Correct |
6 ms |
6744 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
17 ms |
6748 KB |
Output is correct |
2 |
Correct |
17 ms |
6744 KB |
Output is correct |
3 |
Correct |
334 ms |
15368 KB |
Output is correct |
4 |
Correct |
324 ms |
18804 KB |
Output is correct |
5 |
Correct |
346 ms |
20660 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
4 ms |
6492 KB |
Output is correct |
2 |
Correct |
17 ms |
6748 KB |
Output is correct |
3 |
Correct |
17 ms |
6744 KB |
Output is correct |
4 |
Correct |
19 ms |
6748 KB |
Output is correct |
5 |
Correct |
8 ms |
6612 KB |
Output is correct |
6 |
Correct |
6 ms |
6744 KB |
Output is correct |
7 |
Correct |
334 ms |
15368 KB |
Output is correct |
8 |
Correct |
324 ms |
18804 KB |
Output is correct |
9 |
Correct |
346 ms |
20660 KB |
Output is correct |
10 |
Correct |
352 ms |
15184 KB |
Output is correct |
11 |
Correct |
317 ms |
13272 KB |
Output is correct |
12 |
Correct |
332 ms |
19228 KB |
Output is correct |
13 |
Correct |
355 ms |
20824 KB |
Output is correct |
14 |
Correct |
330 ms |
19004 KB |
Output is correct |