結果
| 問題 | No.1124 Earthquake Safety |
| ユーザー |
 uwi
|
| 提出日時 | 2020-07-22 23:17:34 |
| 言語 | Java (openjdk 23) |
| 結果 |
AC
|
| 実行時間 | 715 ms / 3,000 ms |
| コード長 | 7,675 bytes |
| コンパイル時間 | 4,585 ms |
| コンパイル使用メモリ | 88,628 KB |
| 実行使用メモリ | 110,628 KB |
| 最終ジャッジ日時 | 2024-06-23 01:01:46 |
| 合計ジャッジ時間 | 34,837 ms |
|
ジャッジサーバーID （参考情報） |
judge4 / judge3 |
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| ファイルパターン | 結果 |
|---|---|
| other | AC * 58 |
ソースコード
package contest200722;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 F {InputStream is;PrintWriter out;String INPUT = "";void solve(){int n = 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[][] pars = parents3(g, 0);int[] par = pars[0], ord = pars[1], dep = pars[2];Datum[] res = omnidirectionalTreeDP(g, par, ord);long ans = 0;long px = pow(2, n-1, mod);for(Datum v : res){ans += 2*v.v + v.d;}out.println(ans%mod*px%mod);}public static class Datum{long v;long d;public Datum(){v = 0;d = 0;}public Datum(int cur){v = 0;d = 1;}@Overridepublic String toString() {return "Datum [v=" + v + ", d=" + d + "]";}}public static Datum zero = new Datum();public static Datum merge(Datum a, Datum b){Datum ret = new Datum();ret.v = (a.v + b.v + a.d * b.d) % mod;ret.d = (a.d + b.d) % mod;return ret;}public static Datum promote(Datum d, int... e){Datum ret = new Datum();ret.d = d.d * i2 % mod;ret.v = d.v * i2 % mod;return ret;}public static Datum[] omnidirectionalTreeDP(int[][] g, int[] par, int[] ord) {int n = g.length;int root = ord[0];Datum[] dp = new Datum[n];// upfor(int i = n-1;i >= 0;i--){int cur = ord[i];Datum ldp = new Datum(cur);for(int e : g[cur]){if(par[cur] == e)continue;ldp = merge(ldp, promote(dp[e], e));}dp[cur] = ldp;}// downDatum[] prefix = new Datum[n+1];Datum[] fall = new Datum[n];fall[root] = zero;for(int i = 0;i < n;i++){int cur = ord[i];prefix[0] = zero;Datum suffix = merge(new Datum(cur), fall[cur]);for(int j = 0;j < g[cur].length;j++){int e = g[cur][j];prefix[j+1] = par[cur] == e ? prefix[j] : merge(prefix[j], promote(dp[e], e));}for(int j = 0;j < g[cur].length;j++){int e = g[cur][g[cur].length-1-j];if(par[cur] != e){fall[e] = promote(merge(prefix[g[cur].length-1-j], suffix), e);}suffix = par[cur] == e ? suffix : merge(suffix, promote(dp[e], e));}}for(int i = 0;i < n;i++){dp[i] = merge(fall[i], dp[i]);}return dp;}public static Datum[] omnidirectionalTreeDP(int[][][] g, int[] par, int[] ord) {int n = g.length;int root = ord[0];Datum[] dp = new Datum[n];// upfor(int i = n-1;i >= 0;i--){int cur = ord[i];Datum ldp = new Datum(cur);for(int[] e : g[cur]){if(par[cur] == e[0])continue;ldp = merge(ldp, promote(dp[e[0]], e));}dp[cur] = ldp;}// downDatum[] prefix = new Datum[n+1];Datum[] fall = new Datum[n];fall[root] = zero;for(int i = 0;i < n;i++){int cur = ord[i];prefix[0] = zero;Datum suffix = merge(new Datum(cur), fall[cur]);for(int j = 0;j < g[cur].length;j++){int[] e = g[cur][j];prefix[j+1] = par[cur] == e[0] ? prefix[j] : merge(prefix[j], promote(dp[e[0]], e));}for(int j = 0;j < g[cur].length;j++){int[] e = g[cur][g[cur].length-1-j];if(par[cur] != e[0]){fall[e[0]] = promote(merge(prefix[g[cur].length-1-j], suffix), e);}suffix = par[cur] == e[0] ? suffix : merge(suffix, promote(dp[e[0]], e));}}for(int i = 0;i < n;i++){dp[i] = merge(fall[i], dp[i]);}return dp;}public static long pow(long a, long n, long mod) {// a %= mod;long ret = 1;int x = 63 - Long.numberOfLeadingZeros(n);for (; x >= 0; x--) {ret = ret * ret % mod;if (n << 63 - x < 0)ret = ret * a % mod;}return ret;}static int mod = 1000000007;static long i2 = invl(2, mod);public static long invl(long a, long mod) {long b = mod;long p = 1, q = 0;while (b > 0) {long c = a / b;long d;d = a;a = b;b = d % b;d = p;p = q;q = d - c * q;}return p < 0 ? p + mod : p;}public static int[][] parents3(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 };}static int[][] packU(int n, int[] from, int[] to) {int[][] g = new int[n][];int[] p = new int[n];for (int f : from)p[f]++;for (int t : to)p[t]++;for (int i = 0; i < n; i++)g[i] = new int[p[i]];for (int i = 0; i < from.length; i++) {g[from[i]][--p[from[i]]] = to[i];g[to[i]][--p[to[i]]] = from[i];}return g;}void run() throws Exception{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 F().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)); }}