#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
int add (int a, int b) {
a += b; if (a >= MOD) a -= MOD;
return a;
}
int sub (int a, int b) {
a -= b; if (a < 0) a += MOD;
return a;
}
int mul (int a, int b) {
return (a * 1ll * b) % MOD;
}
const int MAXN = 5e5 + 25;
int dp[MAXN][27];
int n, m, type1[MAXN], type2[MAXN];
int main () {
ios::sync_with_stdio(0); cin.tie(0);
cin >> n >> m;
for (int i = 1; i <= m; i++) {
int a, b;
cin >> a >> b;
int l = min(a, b), r = max(a, b);
if (a > b) {
type1[l] = max(type1[l], r);
} else {
type2[l] = max(type2[l], r);
}
}
for (int i = 0; i < 26; i++) {
dp[1][i] = 1;
}
vector <pair <int, int>> s1, s2;
s1.push_back({1, type1[1]});
s2.push_back({1, type2[1]});
for (int i = 2; i <= n; i++) {
for (int j = 0; j < 26; j++) {
int l = 0, r = (int)s2.size() - 1, ans = -1;
while (l <= r) {
int mid = (l + r) / 2;
if (s2[mid].second >= i) {
l = mid + 1; ans = mid;
} else {
r = mid - 1;
}
}
for (int k = 0; k < j; k++) {
dp[i][j] = add(dp[i][j], sub(dp[i - 1][k], dp[s2[ans].first][k]));
}
l = 0, r = (int)s1.size() - 1, ans = -1;
while (l <= r) {
int mid = (l + r) / 2;
if (s1[mid].second >= i) {
l = mid + 1; ans = mid;
} else {
r = mid - 1;
}
}
for (int k = j + 1; k < 26; k++) {
dp[i][j] = add(dp[i][j], sub(dp[i - 1][k], dp[s1[ans].first][k]));
}
dp[i][j] = add(dp[i][j], dp[i - 1][j]);
}
while (!s1.empty() && s1.back().second < type1[i]) s1.pop_back();
s1.push_back({i, type1[i]});
while (!s2.empty() && s2.back().second < type2[i]) s2.pop_back();
s2.push_back({i, type2[i]});
}
int sum = 0;
for (int i = 0; i < 26; i++) {
sum = add(sum, dp[n][i]);
}
cout << sum << '\n';
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2396 KB |
Output is correct |
2 |
Correct |
0 ms |
2396 KB |
Output is correct |
3 |
Correct |
0 ms |
2396 KB |
Output is correct |
4 |
Correct |
0 ms |
2396 KB |
Output is correct |
5 |
Correct |
1 ms |
2396 KB |
Output is correct |
6 |
Correct |
1 ms |
2396 KB |
Output is correct |
7 |
Correct |
1 ms |
2396 KB |
Output is correct |
8 |
Correct |
1 ms |
2396 KB |
Output is correct |
9 |
Correct |
0 ms |
2396 KB |
Output is correct |
10 |
Correct |
0 ms |
2396 KB |
Output is correct |
11 |
Correct |
0 ms |
2396 KB |
Output is correct |
12 |
Correct |
1 ms |
2648 KB |
Output is correct |
13 |
Correct |
1 ms |
2392 KB |
Output is correct |
14 |
Correct |
1 ms |
2396 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2396 KB |
Output is correct |
2 |
Correct |
0 ms |
2396 KB |
Output is correct |
3 |
Correct |
0 ms |
2396 KB |
Output is correct |
4 |
Correct |
0 ms |
2396 KB |
Output is correct |
5 |
Correct |
1 ms |
2396 KB |
Output is correct |
6 |
Correct |
1 ms |
2396 KB |
Output is correct |
7 |
Correct |
1 ms |
2396 KB |
Output is correct |
8 |
Correct |
1 ms |
2396 KB |
Output is correct |
9 |
Correct |
0 ms |
2396 KB |
Output is correct |
10 |
Correct |
0 ms |
2396 KB |
Output is correct |
11 |
Correct |
0 ms |
2396 KB |
Output is correct |
12 |
Correct |
1 ms |
2648 KB |
Output is correct |
13 |
Correct |
1 ms |
2392 KB |
Output is correct |
14 |
Correct |
1 ms |
2396 KB |
Output is correct |
15 |
Correct |
1 ms |
2392 KB |
Output is correct |
16 |
Correct |
1 ms |
2396 KB |
Output is correct |
17 |
Incorrect |
1 ms |
2396 KB |
Output isn't correct |
18 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2396 KB |
Output is correct |
2 |
Correct |
0 ms |
2396 KB |
Output is correct |
3 |
Correct |
1 ms |
2396 KB |
Output is correct |
4 |
Correct |
0 ms |
2504 KB |
Output is correct |
5 |
Correct |
721 ms |
57484 KB |
Output is correct |
6 |
Correct |
712 ms |
63824 KB |
Output is correct |
7 |
Correct |
725 ms |
63716 KB |
Output is correct |
8 |
Correct |
710 ms |
63828 KB |
Output is correct |
9 |
Correct |
734 ms |
63788 KB |
Output is correct |
10 |
Correct |
28 ms |
4432 KB |
Output is correct |
11 |
Correct |
1 ms |
2392 KB |
Output is correct |
12 |
Correct |
1 ms |
2396 KB |
Output is correct |
13 |
Correct |
894 ms |
63716 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2396 KB |
Output is correct |
2 |
Correct |
0 ms |
2396 KB |
Output is correct |
3 |
Correct |
0 ms |
2396 KB |
Output is correct |
4 |
Correct |
0 ms |
2396 KB |
Output is correct |
5 |
Correct |
1 ms |
2396 KB |
Output is correct |
6 |
Correct |
1 ms |
2396 KB |
Output is correct |
7 |
Correct |
1 ms |
2396 KB |
Output is correct |
8 |
Correct |
1 ms |
2396 KB |
Output is correct |
9 |
Correct |
0 ms |
2396 KB |
Output is correct |
10 |
Correct |
0 ms |
2396 KB |
Output is correct |
11 |
Correct |
0 ms |
2396 KB |
Output is correct |
12 |
Correct |
1 ms |
2648 KB |
Output is correct |
13 |
Correct |
1 ms |
2392 KB |
Output is correct |
14 |
Correct |
1 ms |
2396 KB |
Output is correct |
15 |
Correct |
1 ms |
2392 KB |
Output is correct |
16 |
Correct |
1 ms |
2396 KB |
Output is correct |
17 |
Incorrect |
1 ms |
2396 KB |
Output isn't correct |
18 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2396 KB |
Output is correct |
2 |
Correct |
0 ms |
2396 KB |
Output is correct |
3 |
Correct |
0 ms |
2396 KB |
Output is correct |
4 |
Correct |
0 ms |
2396 KB |
Output is correct |
5 |
Correct |
1 ms |
2396 KB |
Output is correct |
6 |
Correct |
1 ms |
2396 KB |
Output is correct |
7 |
Correct |
1 ms |
2396 KB |
Output is correct |
8 |
Correct |
1 ms |
2396 KB |
Output is correct |
9 |
Correct |
0 ms |
2396 KB |
Output is correct |
10 |
Correct |
0 ms |
2396 KB |
Output is correct |
11 |
Correct |
0 ms |
2396 KB |
Output is correct |
12 |
Correct |
1 ms |
2648 KB |
Output is correct |
13 |
Correct |
1 ms |
2392 KB |
Output is correct |
14 |
Correct |
1 ms |
2396 KB |
Output is correct |
15 |
Correct |
1 ms |
2392 KB |
Output is correct |
16 |
Correct |
1 ms |
2396 KB |
Output is correct |
17 |
Incorrect |
1 ms |
2396 KB |
Output isn't correct |
18 |
Halted |
0 ms |
0 KB |
- |