結果
| 問題 |
No.1227 I hate ThREE
|
| コンテスト | |
| ユーザー |
 uwi
|
| 提出日時 | 2020-09-12 02:20:21 |
| 言語 | Java (openjdk 23) |
| 結果 |
AC
|
| 実行時間 | 235 ms / 2,000 ms |
| コード長 | 6,198 bytes |
| コンパイル時間 | 4,129 ms |
| コンパイル使用メモリ | 86,548 KB |
| 実行使用メモリ | 77,896 KB |
| 最終ジャッジ日時 | 2025-01-02 06:04:40 |
| 合計ジャッジ時間 | 10,437 ms |
|
ジャッジサーバーID （参考情報） |
judge5 / judge4 |
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| ファイルパターン | 結果 |
|---|---|
| sample | AC * 3 |
| other | AC * 33 |
ソースコード
package contest200911;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;
public class E2 {
InputStream is;
PrintWriter out;
String INPUT = "";
void solve() {
BarrettInt bi = new BarrettInt(1000000007);
int n = ni(), C = ni();
int[] from = new int[n - 1];
int[] to = new int[n - 1];
for (int i = 0; i < n - 1; i++) {
from[i] = ni() - 1;
to[i] = ni() - 1;
}
int[][] g = packU(n, from, to);
int mod = 1000000007;
int[][] pars = parents(g, 0);
int[] par = pars[0], ord = pars[1];
long ans = 0;
for (int j = 1; j <= 3; j++) {
ans += solve((C - j) / 3 + 1, n, par, ord, mod, g, bi);
}
out.println(ans%mod);
}
long solve(int C, int n, int[] par, int[] ord, int mod, int[][] g, BarrettInt bi)
{
int T = Math.min(2*n+5, C);
int[][] dp = new int[n][T];
for (int i = n - 1; i >= 0; i--) {
int cur = ord[i];
for (int j = 0; j < T; j++) {
long t = 1;
for (int e : g[cur]) {
if (par[cur] == e) continue;
// t = t * ((j - 1 >= 0 ? dp[e][j - 1] : 0) + (j + 1 < T ? dp[e][j+1] : 0)) % mod;
t = bi.modh(t * ((j - 1 >= 0 ? dp[e][j - 1] : 0) + (j + 1 < T ? dp[e][j+1] : 0)));
}
dp[cur][j] = (int)t;
}
}
long ans = 0;
for(int i = 0;i < T;i++){
ans += dp[0][i];
}
if(T < C)ans += (long)dp[0][n+1] * (C-T);
ans %= mod;
return ans;
}
public static class BarrettInt {
public int mod;
public long M;
public int h;
public BarrettInt(int mod)
{
this.mod = mod;
long K = Integer.highestOneBit(mod)<<1;
h = Long.numberOfTrailingZeros(K)*2;
M = K*K/mod;
}
public long mod(long a)
{
long v = M*(a&mask);
long bl = v&mask;
v = (v>>>31) + M*(a>>>31);
bl |= (v&mask)<<31;
long q = bl>>>h|v>>>31<<62-h;
long r = a-q*mod;
return r < mod ? r : r-mod;
}
public long modh(long a)
{
long r = a-((M*(a&mask)>>>31)+M*(a>>>31)>>>h-31)*mod;
return r < mod ? r : r-mod;
}
public long modl(long a)
{
long r = a-(M*a>>>h)*mod;
return r < mod ? r : r-mod;
}
private static final long mask = (1L<<31)-1;
}
public static int[][] parents(int[][] g, int root) {
int n = g.length;
int[] par = new int[n];
Arrays.fill(par, -1);
int[] depth = new int[n];
depth[0] = 0;
int[] q = new int[n];
q[0] = root;
for (int p = 0, r = 1; p < r; p++) {
int cur = q[p];
for (int nex : g[cur]) {
if (par[cur] != nex) {
q[r++] = nex;
par[nex] = cur;
depth[nex] = depth[cur] + 1;
}
}
}
return new int[][]{par, q, depth};
}
public static int[][] packU(int n, int[] from, int[] to) {
return packU(n, from, to, from.length);
}
public static int[][] packU(int n, int[] from, int[] to, int sup) {
int[][] g = new int[n][];
int[] p = new int[n];
for (int i = 0; i < sup; i++) p[from[i]]++;
for (int i = 0; i < sup; i++) p[to[i]]++;
for (int i = 0; i < n; i++) g[i] = new int[p[i]];
for (int i = 0; i < sup; i++) {
g[from[i]][--p[from[i]]] = to[i];
g[to[i]][--p[to[i]]] = from[i];
}
return g;
}
void run() throws Exception
{
// int n = 1000, m = 99999;
// Random gen = new Random(1);
// StringBuilder sb = new StringBuilder();
// sb.append(n + " ");
// sb.append(1000000000 + " ");
// for (int i = 0; i < n-1; i++) {
// sb.append(i+2 + " ");
// sb.append(i+1 + " ");//gen.nextInt(i+1) + 1 + " ");
// }
// INPUT = sb.toString();
is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
out = new PrintWriter(System.out);
long s = System.currentTimeMillis();
solve();
out.flush();
if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
// Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){
// @Override
// public void run() {
// long s = System.currentTimeMillis();
// solve();
// out.flush();
// if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
// }
// };
// t.start();
// t.join();
}
public static void main(String[] args) throws Exception { new E2().run(); }
private byte[] inbuf = new byte[1024];
public int lenbuf = 0, ptrbuf = 0;
private int readByte()
{
if(lenbuf == -1)throw new InputMismatchException();
if(ptrbuf >= lenbuf){
ptrbuf = 0;
try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
if(lenbuf <= 0)return -1;
}
return inbuf[ptrbuf++];
}
private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
private double nd() { return Double.parseDouble(ns()); }
private char nc() { return (char)skip(); }
private String ns()
{
int b = skip();
StringBuilder sb = new StringBuilder();
while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
sb.appendCodePoint(b);
b = readByte();
}
return sb.toString();
}
private char[] ns(int n)
{
char[] buf = new char[n];
int b = skip(), p = 0;
while(p < n && !(isSpaceChar(b))){
buf[p++] = (char)b;
b = readByte();
}
return n == p ? buf : Arrays.copyOf(buf, p);
}
private int[] na(int n)
{
int[] a = new int[n];
for(int i = 0;i < n;i++)a[i] = ni();
return a;
}
private long[] nal(int n)
{
long[] a = new long[n];
for(int i = 0;i < n;i++)a[i] = nl();
return a;
}
private char[][] nm(int n, int m) {
char[][] map = new char[n][];
for(int i = 0;i < n;i++)map[i] = ns(m);
return map;
}
private int[][] nmi(int n, int m) {
int[][] map = new int[n][];
for(int i = 0;i < n;i++)map[i] = na(m);
return map;
}
private int ni() { return (int)nl(); }
private long nl()
{
long num = 0;
int b;
boolean minus = false;
while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
if(b == '-'){
minus = true;
b = readByte();
}
while(true){
if(b >= '0' && b <= '9'){
num = num * 10 + (b - '0');
}else{
return minus ? -num : num;
}
b = readByte();
}
}
private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}