#include <bits/stdc++.h>
using namespace std;
#define fileio() freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#define fastio() cin.tie(0), ios_base::sync_with_stdio(0)
#define pb push_back
#define endl "\n"
#define sp " "
#define pii pair<int, int>
#define st first
#define nd second
#define N 100005
#define int long long
const int modulo = 1e9 + 7;
vector<pii> adj[N];
int dp[N][2][2], edge[N][2];
int add(int a, int b)
{
if (a + b < modulo) return a + b;
return a + b - modulo;
}
int mul(int a, int b)
{
return (a * b) % modulo;
}
int subs(int a, int b)
{
if (a < b) return a - b + modulo;
return a - b;
}
int fe(int a, int b)
{
if (b == 0) return 1;
if (b % 2) return mul(a, fe(a, b - 1));
int tmp = fe(a, b / 2);
return mul(tmp, tmp);
}
int f(int i, int j, int turn)
{
if (dp[i][j][turn] != -1) return dp[i][j][turn];
int node = edge[i][j];
int root = edge[i][1 - j];
if (adj[node].size() == 1)
{
if (turn == 1) return 1;
return 0;
}
int ans = 0;
if (turn == 0) ans = 1;
for (auto k : adj[node])
{
int curr = edge[k.st][k.nd];
if (curr == root) continue;
if (turn == 1) ans |= f(k.st, k.nd, turn ^ 1);
if (turn == 0) ans &= f(k.st, k.nd, turn ^ 1);
}
return dp[i][j][turn] = ans;
}
int32_t main()
{
//fileio();
fastio();
int n, d;
cin>>n>>d;
for (int i = 1; i <= n; i++)
{
int u, v;
cin>>u>>v;
adj[u].pb({i, 1});
adj[v].pb({i, 0});
edge[i][0] = u;
edge[i][1] = v;
}
cout<<fe(4, d)<<endl;
cerr<<"time taken : "<<(float)clock() / CLOCKS_PER_SEC<<" seconds\n";
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
2644 KB |
Output is correct |
2 |
Incorrect |
2 ms |
2644 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2644 KB |
Output is correct |
2 |
Correct |
2 ms |
2644 KB |
Output is correct |
3 |
Correct |
2 ms |
2644 KB |
Output is correct |
4 |
Correct |
2 ms |
2644 KB |
Output is correct |
5 |
Correct |
3 ms |
2676 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2644 KB |
Output is correct |
2 |
Incorrect |
1 ms |
2644 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2644 KB |
Output is correct |
2 |
Incorrect |
1 ms |
2644 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2644 KB |
Output is correct |
2 |
Incorrect |
1 ms |
2644 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2644 KB |
Output is correct |
2 |
Incorrect |
1 ms |
2644 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
2644 KB |
Output is correct |
2 |
Incorrect |
1 ms |
2644 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
2644 KB |
Output is correct |
2 |
Incorrect |
2 ms |
2644 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |