結果
問題 | No.758 VVVVV |
ユーザー |
👑 |
提出日時 | 2019-04-05 07:38:26 |
言語 | D (dmd 2.109.1) |
結果 |
AC
|
実行時間 | 118 ms / 2,000 ms |
コード長 | 3,103 bytes |
コンパイル時間 | 1,066 ms |
コンパイル使用メモリ | 121,960 KB |
実行使用メモリ | 25,104 KB |
最終ジャッジ日時 | 2024-06-13 04:49:49 |
合計ジャッジ時間 | 3,760 ms |
ジャッジサーバーID (参考情報) |
judge1 / judge5 |
(要ログイン)
ファイルパターン | 結果 |
---|---|
sample | AC * 3 |
other | AC * 23 |
ソースコード
import std.conv, std.functional, std.stdio, std.string;import std.algorithm, std.array, std.bigint, std.container, std.math, std.numeric, std.range, std.regex, std.typecons;import core.bitop;class EOFException : Throwable { this() { super("EOF"); } }string[] tokens;string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }int readInt() { return readToken.to!int; }long readLong() { return readToken.to!long; }real readReal() { return readToken.to!real; }bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1;(unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }enum MO = 10L^^9 + 7;enum LIM = 3 * 10^^5;long[] inv, fac, invFac;void prepare() {inv = new long[LIM];fac = new long[LIM];invFac = new long[LIM];inv[1] = 1;foreach (i; 2 .. LIM) {inv[i] = MO - ((MO / i) * inv[cast(size_t)(MO % i)]) % MO;}fac[0] = invFac[0] = 1;foreach (i; 1 .. LIM) {fac[i] = (fac[i - 1] * i) % MO;invFac[i] = (invFac[i - 1] * inv[i]) % MO;}}long binom(long n, long k) {if (0 <= k && k <= n) {assert(n < LIM);return fac[cast(size_t)(n)] * invFac[cast(size_t)(k)] % MO * invFac[cast(size_t)(n - k)] % MO;} else {return 0;}}int N;int[] A, B;int[][] G;int cntLeaf;void dfs(int u, int p) {bool isLeaf = true;foreach (v; G[u]) {if (v != p) {isLeaf = false;dfs(v, u);}}if (isLeaf) {++cntLeaf;}}void main() {prepare();debug {enum lim = 10;auto dp = new long[][][](lim, lim, lim);foreach (a; 1 .. lim) foreach (b; 1 .. lim) {dp[a][b][1] = 1;foreach (k; 2 .. lim) {foreach (aa; 1 .. a) foreach (bb; 1 .. b) {if (aa >= bb) {dp[a][b][k] += dp[aa][bb][k - 1];}}}}foreach (n; 1 .. lim) {foreach (k; 1 .. lim) {write(" ", dp[n][n][k]);}writeln();}}try {for (; ; ) {N = readInt();A = new int[N - 1];B = new int[N - 1];foreach (i; 0 .. N - 1) {A[i] = readInt() - 1;B[i] = readInt() - 1;}G = new int[][N];foreach (i; 0 .. N - 1) {G[A[i]] ~= B[i];G[B[i]] ~= A[i];}cntLeaf = 0;dfs(0, -1);long ans = 1;if (N > 1) {ans *= binom(N - 1 - 1, cntLeaf - 1);ans %= MO;ans *= binom(N - 1, cntLeaf - 1);ans %= MO;ans *= inv[cntLeaf];ans %= MO;}writeln(ans);}} catch (EOFException e) {}}