#include <cctype>
#include <cstdio>
#include <cstdlib>
#include <cstring>
int nextInt() {
char ch;
while (!isdigit(ch = getchar())) {}
int res = ch - '0';
while (isdigit(ch = getchar())) res = 10 * res + ch - '0';
return res;
}
const int N = 2000000 + 10, S = 40 * N, MOD = 1000000007;
int n, a[N], b[N], c[N], id[N];
int adj[N], to[S], next[S];
void link(int a, int b) {
static int cnt = 2;
to[cnt] = b;
next[cnt] = adj[a];
adj[a] = cnt++;
}
int buffer[S], *pool[N];
void update(int p, int v) {
for (; p <= 2 * n; p += p & -p) pool[p][++pool[p][0]] = v;
}
void query(int p, int v) {
for (; p; p ^= p & -p) {
int &y = pool[p][0];
if (!y) continue;
int x = pool[p][y];
if (b[x] < a[v]) continue;
for (; y; --y) {
int u = pool[p][y];
if (b[u] >= a[v]) link(u, v), link(v, u); else break;
}
pool[p][++y] = x;
}
}
int tag[N];
void fail() {
puts("0");
exit(0);
}
void dfs(int a) {
int c = 3 - tag[a];
for (int i = adj[a]; i; i = next[i]) {
int b = to[i];
if (!tag[b]) {
tag[b] = c;
dfs(b);
} else if (tag[b] != c) {
fail();
}
}
}
class {
int data[N];
void add(int p, int v) {
for (; p <= 2 * n; p += p & -p) data[p] += v;
}
public:
void clear() {
memset(data, 0, sizeof data);
}
void add(int l, int r, int v) {
add(l, v);
add(r + 1, -v);
}
int query(int p) {
int res = 0;
for (; p; p ^= p & -p) res += data[p];
return res;
}
} bit;
void check(int y) {
bit.clear();
for (int i = 1; i <= 2 * n; ++i) {
int x = id[i];
if (tag[x] != y) continue;
if (c[i] > i) {
bit.add(1, i, 1);
} else {
bit.add(1, c[i], -1);
if (bit.query(c[i])) fail();
bit.add(c[i], i, 1);
}
}
}
int main() {
scanf("%d", &n);
for (int i = 1, *top = buffer; i <= 2 * n; ++i) {
pool[i] = top;
top += (i & -i) + 1;
}
for (int i = 1; i <= n; ++i) a[i] = nextInt(), b[i] = nextInt();
for (int i = 1; i <= n; ++i) c[a[i]] = b[i], c[b[i]] = a[i], id[a[i]] = id[b[i]] = i;
for (int i = 1; i <= 2 * n; ++i) {
if (c[i] > i) continue;
query(c[i], id[i]);
update(c[i], id[i]);
}
int cnt = 0;
for (int i = 1; i <= n; ++i) if (!tag[i]) ++cnt, tag[i] = 1, dfs(i);
check(1);
check(2);
int ans = 1;
while (cnt--) ans = 2 * ans % MOD;
printf("%d\n", ans);
return 0;
}
Compilation message
port_facility.cpp: In function 'int main()':
port_facility.cpp:103:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d", &n);
^
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
1008936 KB |
Output is correct |
2 |
Correct |
0 ms |
1008936 KB |
Output is correct |
3 |
Correct |
0 ms |
1008936 KB |
Output is correct |
4 |
Correct |
3 ms |
1008936 KB |
Output is correct |
5 |
Correct |
0 ms |
1008936 KB |
Output is correct |
6 |
Correct |
3 ms |
1008936 KB |
Output is correct |
7 |
Correct |
3 ms |
1008936 KB |
Output is correct |
8 |
Correct |
3 ms |
1008936 KB |
Output is correct |
9 |
Correct |
0 ms |
1008936 KB |
Output is correct |
10 |
Correct |
3 ms |
1008936 KB |
Output is correct |
11 |
Correct |
0 ms |
1008936 KB |
Output is correct |
12 |
Correct |
0 ms |
1008936 KB |
Output is correct |
13 |
Correct |
0 ms |
1008936 KB |
Output is correct |
14 |
Correct |
3 ms |
1008936 KB |
Output is correct |
15 |
Correct |
3 ms |
1008936 KB |
Output is correct |
16 |
Correct |
0 ms |
1008936 KB |
Output is correct |
17 |
Correct |
3 ms |
1008936 KB |
Output is correct |
18 |
Correct |
3 ms |
1008936 KB |
Output is correct |
19 |
Correct |
3 ms |
1008936 KB |
Output is correct |
20 |
Correct |
0 ms |
1008936 KB |
Output is correct |
21 |
Correct |
0 ms |
1008936 KB |
Output is correct |
22 |
Correct |
0 ms |
1008936 KB |
Output is correct |
23 |
Correct |
0 ms |
1008936 KB |
Output is correct |
24 |
Correct |
0 ms |
1008936 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
1008936 KB |
Output is correct |
2 |
Correct |
0 ms |
1008936 KB |
Output is correct |
3 |
Correct |
0 ms |
1008936 KB |
Output is correct |
4 |
Correct |
3 ms |
1008936 KB |
Output is correct |
5 |
Correct |
0 ms |
1008936 KB |
Output is correct |
6 |
Correct |
3 ms |
1008936 KB |
Output is correct |
7 |
Correct |
3 ms |
1008936 KB |
Output is correct |
8 |
Correct |
3 ms |
1008936 KB |
Output is correct |
9 |
Correct |
0 ms |
1008936 KB |
Output is correct |
10 |
Correct |
3 ms |
1008936 KB |
Output is correct |
11 |
Correct |
0 ms |
1008936 KB |
Output is correct |
12 |
Correct |
0 ms |
1008936 KB |
Output is correct |
13 |
Correct |
0 ms |
1008936 KB |
Output is correct |
14 |
Correct |
3 ms |
1008936 KB |
Output is correct |
15 |
Correct |
3 ms |
1008936 KB |
Output is correct |
16 |
Correct |
0 ms |
1008936 KB |
Output is correct |
17 |
Correct |
3 ms |
1008936 KB |
Output is correct |
18 |
Correct |
3 ms |
1008936 KB |
Output is correct |
19 |
Correct |
3 ms |
1008936 KB |
Output is correct |
20 |
Correct |
0 ms |
1008936 KB |
Output is correct |
21 |
Correct |
0 ms |
1008936 KB |
Output is correct |
22 |
Correct |
0 ms |
1008936 KB |
Output is correct |
23 |
Correct |
0 ms |
1008936 KB |
Output is correct |
24 |
Correct |
0 ms |
1008936 KB |
Output is correct |
25 |
Correct |
3 ms |
1008936 KB |
Output is correct |
26 |
Correct |
3 ms |
1008936 KB |
Output is correct |
27 |
Correct |
0 ms |
1008936 KB |
Output is correct |
28 |
Correct |
6 ms |
1008936 KB |
Output is correct |
29 |
Correct |
0 ms |
1008936 KB |
Output is correct |
30 |
Correct |
3 ms |
1008936 KB |
Output is correct |
31 |
Correct |
0 ms |
1008936 KB |
Output is correct |
32 |
Correct |
0 ms |
1008936 KB |
Output is correct |
33 |
Correct |
0 ms |
1008936 KB |
Output is correct |
34 |
Correct |
0 ms |
1008936 KB |
Output is correct |
35 |
Correct |
3 ms |
1008936 KB |
Output is correct |
36 |
Correct |
6 ms |
1008936 KB |
Output is correct |
37 |
Correct |
0 ms |
1008936 KB |
Output is correct |
38 |
Correct |
0 ms |
1008936 KB |
Output is correct |
39 |
Correct |
0 ms |
1008936 KB |
Output is correct |
40 |
Correct |
6 ms |
1008936 KB |
Output is correct |
41 |
Correct |
3 ms |
1008936 KB |
Output is correct |
42 |
Correct |
0 ms |
1008936 KB |
Output is correct |
43 |
Correct |
0 ms |
1008936 KB |
Output is correct |
44 |
Correct |
0 ms |
1008936 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
1008936 KB |
Output is correct |
2 |
Correct |
0 ms |
1008936 KB |
Output is correct |
3 |
Correct |
0 ms |
1008936 KB |
Output is correct |
4 |
Correct |
3 ms |
1008936 KB |
Output is correct |
5 |
Correct |
0 ms |
1008936 KB |
Output is correct |
6 |
Correct |
3 ms |
1008936 KB |
Output is correct |
7 |
Correct |
3 ms |
1008936 KB |
Output is correct |
8 |
Correct |
3 ms |
1008936 KB |
Output is correct |
9 |
Correct |
0 ms |
1008936 KB |
Output is correct |
10 |
Correct |
3 ms |
1008936 KB |
Output is correct |
11 |
Correct |
0 ms |
1008936 KB |
Output is correct |
12 |
Correct |
0 ms |
1008936 KB |
Output is correct |
13 |
Correct |
0 ms |
1008936 KB |
Output is correct |
14 |
Correct |
3 ms |
1008936 KB |
Output is correct |
15 |
Correct |
3 ms |
1008936 KB |
Output is correct |
16 |
Correct |
0 ms |
1008936 KB |
Output is correct |
17 |
Correct |
3 ms |
1008936 KB |
Output is correct |
18 |
Correct |
3 ms |
1008936 KB |
Output is correct |
19 |
Correct |
3 ms |
1008936 KB |
Output is correct |
20 |
Correct |
0 ms |
1008936 KB |
Output is correct |
21 |
Correct |
0 ms |
1008936 KB |
Output is correct |
22 |
Correct |
0 ms |
1008936 KB |
Output is correct |
23 |
Correct |
0 ms |
1008936 KB |
Output is correct |
24 |
Correct |
0 ms |
1008936 KB |
Output is correct |
25 |
Correct |
3 ms |
1008936 KB |
Output is correct |
26 |
Correct |
3 ms |
1008936 KB |
Output is correct |
27 |
Correct |
0 ms |
1008936 KB |
Output is correct |
28 |
Correct |
6 ms |
1008936 KB |
Output is correct |
29 |
Correct |
0 ms |
1008936 KB |
Output is correct |
30 |
Correct |
3 ms |
1008936 KB |
Output is correct |
31 |
Correct |
0 ms |
1008936 KB |
Output is correct |
32 |
Correct |
0 ms |
1008936 KB |
Output is correct |
33 |
Correct |
0 ms |
1008936 KB |
Output is correct |
34 |
Correct |
0 ms |
1008936 KB |
Output is correct |
35 |
Correct |
3 ms |
1008936 KB |
Output is correct |
36 |
Correct |
6 ms |
1008936 KB |
Output is correct |
37 |
Correct |
0 ms |
1008936 KB |
Output is correct |
38 |
Correct |
0 ms |
1008936 KB |
Output is correct |
39 |
Correct |
0 ms |
1008936 KB |
Output is correct |
40 |
Correct |
6 ms |
1008936 KB |
Output is correct |
41 |
Correct |
3 ms |
1008936 KB |
Output is correct |
42 |
Correct |
0 ms |
1008936 KB |
Output is correct |
43 |
Correct |
0 ms |
1008936 KB |
Output is correct |
44 |
Correct |
0 ms |
1008936 KB |
Output is correct |
45 |
Correct |
66 ms |
1009048 KB |
Output is correct |
46 |
Correct |
99 ms |
1009280 KB |
Output is correct |
47 |
Correct |
73 ms |
1008936 KB |
Output is correct |
48 |
Correct |
93 ms |
1009272 KB |
Output is correct |
49 |
Correct |
69 ms |
1008936 KB |
Output is correct |
50 |
Correct |
29 ms |
1009124 KB |
Output is correct |
51 |
Correct |
43 ms |
1008936 KB |
Output is correct |
52 |
Correct |
56 ms |
1008936 KB |
Output is correct |
53 |
Correct |
49 ms |
1008936 KB |
Output is correct |
54 |
Correct |
39 ms |
1008936 KB |
Output is correct |
55 |
Correct |
36 ms |
1008936 KB |
Output is correct |
56 |
Correct |
36 ms |
1008936 KB |
Output is correct |
57 |
Correct |
63 ms |
1008936 KB |
Output is correct |
58 |
Correct |
39 ms |
1008936 KB |
Output is correct |
59 |
Correct |
63 ms |
1008936 KB |
Output is correct |
60 |
Correct |
66 ms |
1008936 KB |
Output is correct |
61 |
Correct |
79 ms |
1008936 KB |
Output is correct |
62 |
Correct |
26 ms |
1008936 KB |
Output is correct |
63 |
Correct |
36 ms |
1008936 KB |
Output is correct |
64 |
Correct |
49 ms |
1008936 KB |
Output is correct |
65 |
Correct |
76 ms |
1008936 KB |
Output is correct |
66 |
Correct |
79 ms |
1008936 KB |
Output is correct |
67 |
Correct |
59 ms |
1008936 KB |
Output is correct |
68 |
Correct |
69 ms |
1008936 KB |
Output is correct |
69 |
Correct |
59 ms |
1008936 KB |
Output is correct |
70 |
Correct |
59 ms |
1008936 KB |
Output is correct |
71 |
Correct |
59 ms |
1008936 KB |
Output is correct |
72 |
Correct |
63 ms |
1008936 KB |
Output is correct |
73 |
Correct |
59 ms |
1008936 KB |
Output is correct |
74 |
Correct |
56 ms |
1008936 KB |
Output is correct |
75 |
Correct |
53 ms |
1010668 KB |
Output is correct |
76 |
Correct |
63 ms |
1011936 KB |
Output is correct |
77 |
Correct |
33 ms |
1011936 KB |
Output is correct |
78 |
Correct |
83 ms |
1009228 KB |
Output is correct |
79 |
Correct |
106 ms |
1009072 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
1008936 KB |
Output is correct |
2 |
Correct |
0 ms |
1008936 KB |
Output is correct |
3 |
Correct |
0 ms |
1008936 KB |
Output is correct |
4 |
Correct |
3 ms |
1008936 KB |
Output is correct |
5 |
Correct |
0 ms |
1008936 KB |
Output is correct |
6 |
Correct |
3 ms |
1008936 KB |
Output is correct |
7 |
Correct |
3 ms |
1008936 KB |
Output is correct |
8 |
Correct |
3 ms |
1008936 KB |
Output is correct |
9 |
Correct |
0 ms |
1008936 KB |
Output is correct |
10 |
Correct |
3 ms |
1008936 KB |
Output is correct |
11 |
Correct |
0 ms |
1008936 KB |
Output is correct |
12 |
Correct |
0 ms |
1008936 KB |
Output is correct |
13 |
Correct |
0 ms |
1008936 KB |
Output is correct |
14 |
Correct |
3 ms |
1008936 KB |
Output is correct |
15 |
Correct |
3 ms |
1008936 KB |
Output is correct |
16 |
Correct |
0 ms |
1008936 KB |
Output is correct |
17 |
Correct |
3 ms |
1008936 KB |
Output is correct |
18 |
Correct |
3 ms |
1008936 KB |
Output is correct |
19 |
Correct |
3 ms |
1008936 KB |
Output is correct |
20 |
Correct |
0 ms |
1008936 KB |
Output is correct |
21 |
Correct |
0 ms |
1008936 KB |
Output is correct |
22 |
Correct |
0 ms |
1008936 KB |
Output is correct |
23 |
Correct |
0 ms |
1008936 KB |
Output is correct |
24 |
Correct |
0 ms |
1008936 KB |
Output is correct |
25 |
Correct |
3 ms |
1008936 KB |
Output is correct |
26 |
Correct |
3 ms |
1008936 KB |
Output is correct |
27 |
Correct |
0 ms |
1008936 KB |
Output is correct |
28 |
Correct |
6 ms |
1008936 KB |
Output is correct |
29 |
Correct |
0 ms |
1008936 KB |
Output is correct |
30 |
Correct |
3 ms |
1008936 KB |
Output is correct |
31 |
Correct |
0 ms |
1008936 KB |
Output is correct |
32 |
Correct |
0 ms |
1008936 KB |
Output is correct |
33 |
Correct |
0 ms |
1008936 KB |
Output is correct |
34 |
Correct |
0 ms |
1008936 KB |
Output is correct |
35 |
Correct |
3 ms |
1008936 KB |
Output is correct |
36 |
Correct |
6 ms |
1008936 KB |
Output is correct |
37 |
Correct |
0 ms |
1008936 KB |
Output is correct |
38 |
Correct |
0 ms |
1008936 KB |
Output is correct |
39 |
Correct |
0 ms |
1008936 KB |
Output is correct |
40 |
Correct |
6 ms |
1008936 KB |
Output is correct |
41 |
Correct |
3 ms |
1008936 KB |
Output is correct |
42 |
Correct |
0 ms |
1008936 KB |
Output is correct |
43 |
Correct |
0 ms |
1008936 KB |
Output is correct |
44 |
Correct |
0 ms |
1008936 KB |
Output is correct |
45 |
Correct |
66 ms |
1009048 KB |
Output is correct |
46 |
Correct |
99 ms |
1009280 KB |
Output is correct |
47 |
Correct |
73 ms |
1008936 KB |
Output is correct |
48 |
Correct |
93 ms |
1009272 KB |
Output is correct |
49 |
Correct |
69 ms |
1008936 KB |
Output is correct |
50 |
Correct |
29 ms |
1009124 KB |
Output is correct |
51 |
Correct |
43 ms |
1008936 KB |
Output is correct |
52 |
Correct |
56 ms |
1008936 KB |
Output is correct |
53 |
Correct |
49 ms |
1008936 KB |
Output is correct |
54 |
Correct |
39 ms |
1008936 KB |
Output is correct |
55 |
Correct |
36 ms |
1008936 KB |
Output is correct |
56 |
Correct |
36 ms |
1008936 KB |
Output is correct |
57 |
Correct |
63 ms |
1008936 KB |
Output is correct |
58 |
Correct |
39 ms |
1008936 KB |
Output is correct |
59 |
Correct |
63 ms |
1008936 KB |
Output is correct |
60 |
Correct |
66 ms |
1008936 KB |
Output is correct |
61 |
Correct |
79 ms |
1008936 KB |
Output is correct |
62 |
Correct |
26 ms |
1008936 KB |
Output is correct |
63 |
Correct |
36 ms |
1008936 KB |
Output is correct |
64 |
Correct |
49 ms |
1008936 KB |
Output is correct |
65 |
Correct |
76 ms |
1008936 KB |
Output is correct |
66 |
Correct |
79 ms |
1008936 KB |
Output is correct |
67 |
Correct |
59 ms |
1008936 KB |
Output is correct |
68 |
Correct |
69 ms |
1008936 KB |
Output is correct |
69 |
Correct |
59 ms |
1008936 KB |
Output is correct |
70 |
Correct |
59 ms |
1008936 KB |
Output is correct |
71 |
Correct |
59 ms |
1008936 KB |
Output is correct |
72 |
Correct |
63 ms |
1008936 KB |
Output is correct |
73 |
Correct |
59 ms |
1008936 KB |
Output is correct |
74 |
Correct |
56 ms |
1008936 KB |
Output is correct |
75 |
Correct |
53 ms |
1010668 KB |
Output is correct |
76 |
Correct |
63 ms |
1011936 KB |
Output is correct |
77 |
Correct |
33 ms |
1011936 KB |
Output is correct |
78 |
Correct |
83 ms |
1009228 KB |
Output is correct |
79 |
Correct |
106 ms |
1009072 KB |
Output is correct |
80 |
Correct |
1449 ms |
1009860 KB |
Output is correct |
81 |
Correct |
1406 ms |
1009652 KB |
Output is correct |
82 |
Correct |
1303 ms |
1009040 KB |
Output is correct |
83 |
Correct |
1376 ms |
1009668 KB |
Output is correct |
84 |
Correct |
1283 ms |
1009848 KB |
Output is correct |
85 |
Correct |
609 ms |
1008948 KB |
Output is correct |
86 |
Correct |
666 ms |
1009232 KB |
Output is correct |
87 |
Correct |
989 ms |
1008936 KB |
Output is correct |
88 |
Correct |
803 ms |
1008936 KB |
Output is correct |
89 |
Correct |
863 ms |
1008936 KB |
Output is correct |
90 |
Correct |
779 ms |
1008936 KB |
Output is correct |
91 |
Correct |
899 ms |
1008936 KB |
Output is correct |
92 |
Correct |
1316 ms |
1008936 KB |
Output is correct |
93 |
Correct |
949 ms |
1008936 KB |
Output is correct |
94 |
Correct |
1046 ms |
1008936 KB |
Output is correct |
95 |
Correct |
1179 ms |
1008936 KB |
Output is correct |
96 |
Correct |
1343 ms |
1008936 KB |
Output is correct |
97 |
Correct |
513 ms |
1008936 KB |
Output is correct |
98 |
Correct |
623 ms |
1008936 KB |
Output is correct |
99 |
Correct |
636 ms |
1008936 KB |
Output is correct |
100 |
Correct |
2383 ms |
1008936 KB |
Output is correct |
101 |
Correct |
2156 ms |
1008936 KB |
Output is correct |
102 |
Correct |
1036 ms |
1008936 KB |
Output is correct |
103 |
Correct |
1002 ms |
1008936 KB |
Output is correct |
104 |
Correct |
1113 ms |
1008936 KB |
Output is correct |
105 |
Correct |
1073 ms |
1008936 KB |
Output is correct |
106 |
Correct |
859 ms |
1008936 KB |
Output is correct |
107 |
Correct |
1033 ms |
1008936 KB |
Output is correct |
108 |
Correct |
1106 ms |
1008936 KB |
Output is correct |
109 |
Correct |
1053 ms |
1008936 KB |
Output is correct |
110 |
Correct |
1309 ms |
1039424 KB |
Output is correct |
111 |
Correct |
1433 ms |
1040060 KB |
Output is correct |
112 |
Correct |
746 ms |
1040064 KB |
Output is correct |
113 |
Correct |
1379 ms |
1009012 KB |
Output is correct |
114 |
Correct |
1233 ms |
1009616 KB |
Output is correct |