結果
問題 | No.1075 木の上の山 |
ユーザー |
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提出日時 | 2020-06-05 21:42:39 |
言語 | C++14 (gcc 13.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 65 ms / 2,000 ms |
コード長 | 4,073 bytes |
コンパイル時間 | 2,418 ms |
コンパイル使用メモリ | 183,024 KB |
実行使用メモリ | 23,424 KB |
最終ジャッジ日時 | 2024-12-17 13:57:48 |
合計ジャッジ時間 | 4,094 ms |
ジャッジサーバーID (参考情報) |
judge1 / judge5 |
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ファイルパターン | 結果 |
---|---|
sample | AC * 2 |
other | AC * 30 |
ソースコード
#include <bits/stdc++.h>int ri() {int n;scanf("%d", &n);return n;}#define MOD 1000000007template<int mod>struct ModInt{int x;ModInt():x(0){}ModInt(long long y):x(y>=0?y%mod:(mod-(-y)%mod)%mod){}ModInt &operator+=(const ModInt &p){if((x+=p.x)>=mod)x-=mod;return *this;}ModInt &operator-=(const ModInt &p){if((x+=mod-p.x)>=mod)x-=mod;return *this;}ModInt &operator*=(const ModInt &p){x=(int)(1LL*x*p.x%mod);return *this;}ModInt &operator/=(const ModInt &p){*this*=p.inverse();return *this;}ModInt &operator^=(long long p){ModInt res = 1;for (; p; p >>= 1) {if (p & 1) res *= *this;*this *= *this;}return *this = res;}ModInt operator-()const{return ModInt(-x);}ModInt operator+(const ModInt &p)const{return ModInt(*this)+=p;}ModInt operator-(const ModInt &p)const{return ModInt(*this)-=p;}ModInt operator*(const ModInt &p)const{return ModInt(*this)*=p;}ModInt operator/(const ModInt &p)const{return ModInt(*this)/=p;}ModInt operator^(long long p)const{return ModInt(*this)^=p;}bool operator==(const ModInt &p)const{return x==p.x;}bool operator!=(const ModInt &p)const{return x!=p.x;}explicit operator int() const { return x; } // added by QCFiumModInt operator=(const int p) {x = p; return ModInt(*this);} // added by QCFiumModInt inverse()const{int a=x,b=mod,u=1,v=0,t;while(b>0){t=a/b;a-=t*b;std::swap(a,b);u-=t*v;std::swap(u,v);}return ModInt(u);}friend std::ostream &operator<<(std::ostream &os,const ModInt<mod> &p){return os<<p.x;}friend std::istream &operator>>(std::istream &is,ModInt<mod> &a){long long x;is>>x;a=ModInt<mod>(x);return (is);}};typedef ModInt<MOD> mint;struct MComb {std::vector<mint> fact;std::vector<mint> inv;MComb (int n) { // O(n + log(mod))fact = std::vector<mint>(n + 1, 1);for (int i = 1; i <= n; i++) fact[i] = fact[i - 1] * mint(i);inv.resize(n + 1);inv[n] = fact[n] ^ (MOD - 2);for (int i = n; i--; ) inv[i] = inv[i + 1] * mint(i + 1);}mint ncr(int n, int r) {return fact[n] * inv[r] * inv[n - r];}mint npr(int n, int r) {return fact[n] * inv[n - r];}mint nhr(int n, int r) {assert(n + r - 1 < (int) fact.size());return ncr(n + r - 1, r);}};std::vector<std::vector<int> > hen;int k;std::vector<mint> merge(const std::vector<mint> &l, const std::vector<mint> &r) {int n = l.size();std::vector<mint> res(n);mint suml = 0, sumr = 0;for (int i = 0; i < k; i++) {suml += l[i];sumr += r[i];res[i] += suml * r[i];res[i] += sumr * l[i];res[i] -= l[i] * r[i];}return res;}mint res;std::vector<std::vector<mint> > subtree;void dfs0(int i, int prev) {if (prev != -1) hen[i].erase(std::find(hen[i].begin(), hen[i].end(), prev));subtree[i].resize(k);subtree[i][0] = 1;for (auto j : hen[i]) {dfs0(j, i);subtree[i] = merge(subtree[i], subtree[j]);}for (int j = 0; j + 1 < k; j++) subtree[i][j + 1] += subtree[i][j];}void dfs1(int i, int prev, const std::vector<mint> &par_dp) {int m = hen[i].size();mint sumed = 0;for (int j = 0; j < k; j++) {res += subtree[i][j] * (prev == -1 ? 1 : sumed);if (prev != -1) sumed += par_dp[j];}if (m) {std::vector<std::vector<mint> > left(m);std::vector<std::vector<mint> > right(m);std::vector<mint> tmp(k);tmp[0] = 1;left.front() = right.back() = tmp;for (int j = 0; j + 1 < m; j++) left[j + 1] = merge(left[j], subtree[hen[i][j]]);for (int j = m; --j; ) right[j - 1] = merge(right[j], subtree[hen[i][j]]);for (int j = 0; j < m; j++) {auto tmp = merge(merge(left[j], right[j]), par_dp);for (int l = 0; l + 1 < k; l++) tmp[l + 1] += tmp[l];dfs1(hen[i][j], i, tmp);}}}int main() {int n = ri();k = ri();hen.resize(n);for (int i = 1; i < n; i++) {int a = ri() - 1;int b = ri() - 1;hen[a].push_back(b);hen[b].push_back(a);}subtree.resize(n);dfs0(0, -1);std::vector<mint> tmp(k);tmp[0] = 1;dfs1(0, -1, tmp);std::cout << res << std::endl;return 0;}