結果

問題 No.1075 木の上の山
ユーザー leaf_1415leaf_1415
提出日時 2020-06-05 22:52:34
言語 C++11
(gcc 13.3.0)
結果
AC  
実行時間 222 ms / 2,000 ms
コード長 3,679 bytes
コンパイル時間 1,031 ms
コンパイル使用メモリ 83,980 KB
実行使用メモリ 34,988 KB
最終ジャッジ日時 2024-12-17 17:07:43
合計ジャッジ時間 3,914 ms
ジャッジサーバーID
(参考情報)
judge3 / judge4
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other AC * 30
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <iostream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <cassert>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <string>
#include <algorithm>
#include <utility>
#define llint long long
#define inf 1e18
#define rep(x, s, t) for(llint (x) = (s); (x) < (t); (x)++)
#define Rep(x, s, t) for(llint (x) = (s); (x) <= (t); (x)++)
#define chmin(x, y) (x) = min((x), (y))
#define chmax(x, y) (x) = max((x), (y))
#define mod 1000000007
using namespace std;
typedef pair<llint, llint> P;
llint n, k;
vector<llint> G[1005];
typedef pair<llint, llint> P;
int parent[1005];
llint dp[1005][1005], dp2[1005][1005];
llint sum[1005][1005], sum2[1005][1005];
llint get(int u, int v, int x)
{
if(parent[u] == v) return dp2[u][x];
else return dp[v][x];
}
llint getsum(int u, int v, int x)
{
if(parent[u] == v) return sum2[u][x];
else return sum[v][x];
}
void dfs(int v, int p)
{
parent[v] = p;
for(int i = 0; i < G[v].size(); i++){
if(G[v][i] == p) continue;
dfs(G[v][i], v);
}
for(int j = 1; j <= k; j++){
llint mul = 1;
for(int i = 0; i < G[v].size(); i++){
int u = G[v][i];
if(u == p) continue;
mul *= getsum(v, u, j), mul %= mod;
}
dp[v][j] = mul;
sum[v][j] = sum[v][j-1] + dp[v][j], sum[v][j] %= mod;
}
}
llint lsum[1005], rsum[1005];
void dfs2(int v, int p)
{
llint m = G[v].size(), mul;
for(int j = 1; j <= k; j++){
mul = lsum[0] = 1;
for(int i = 0; i < m; i++){
int u = G[v][i];
mul *= getsum(v, u, j), mul %= mod; //
lsum[i+1] = mul;
}
mul = rsum[m+1] = 1;
for(int i = m-1; i >= 0; i--){
int u = G[v][i];
mul *= getsum(v, u, j), mul %= mod; //
rsum[i+1] = mul;
}
for(int i = 0; i < m; i++){
int u = G[v][i];
if(u == p) continue;
dp2[u][j] = lsum[i] * rsum[i+2] % mod;
sum2[u][j] = (sum2[u][j-1] + dp2[u][j]) % mod;
}
}
for(int i = 0; i < G[v].size(); i++){
if(G[v][i] == p) continue;
dfs2(G[v][i], v);
}
}
int size[1005];
bool used[1005];
int sizedfs(int v, int pre)
{
int ret = 1;
for(int i = 0; i < G[v].size(); i++){
if(G[v][i] == pre) continue;
if(used[G[v][i]]) continue;
ret += sizedfs(G[v][i], v);
}
return size[v] = ret;
}
int centdfs(int v, int pre, int sz)
{
for(int i = 0; i < G[v].size(); i++){
if(G[v][i] == pre) continue;
if(used[G[v][i]]) continue;
if(size[G[v][i]] > sz/2) return centdfs(G[v][i], v, sz);
}
return v;
}
llint calcdfs(llint v, llint p, llint k)
{
llint ret = 0;
if(p != -1) ret = getsum(p, v, k-1);
llint mul = 1;
for(int i = 0; i < G[v].size(); i++){
llint u = G[v][i];
if(u == p) continue;
if(used[u]){
mul *= getsum(v, u, k-1), mul %= mod;
continue;
}
mul *= calcdfs(G[v][i], v, k), mul %= mod;
}
ret += mul, ret %= mod;
return ret;
}
llint ans = 0;
void solve(int v)
{
sizedfs(v, -1);
v = centdfs(v, -1, size[v]);
/* */
for(int i = 2; i <= k; i++){
ans += calcdfs(v, -1, i);
ans %= mod;
}
used[v] = true;
for(int i = 0; i < G[v].size(); i++){
if(used[G[v][i]]) continue;
solve(G[v][i]);
}
}
int main(void)
{
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> k;
llint u, v;
for(int i = 1; i <= n-1; i++){
cin >> u >> v;
G[u].push_back(v);
G[v].push_back(u);
}
if(k == 1){
cout << 1 << endl;
return 0;
}
dfs(1, -1);
dfs2(1, -1);
/*for(int i = 1; i <= n; i++){
for(int j = 0; j < G[i].size(); j++){
cout << i << " " << G[i][j] << " : ";
for(int l = 1; l <= k; l++){
cout << get(i, G[i][j], l) << " ";
}
cout << endl;
}
}*/
solve(1);
ans += 1, ans %= mod;
cout << ans << endl;
return 0;
}
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