結果
問題 | No.778 クリスマスツリー |
ユーザー |
![]() |
提出日時 | 2018-12-25 00:21:32 |
言語 | Java (openjdk 23) |
結果 |
AC
|
実行時間 | 428 ms / 2,000 ms |
コード長 | 3,745 bytes |
コンパイル時間 | 2,394 ms |
コンパイル使用メモリ | 82,548 KB |
実行使用メモリ | 91,748 KB |
最終ジャッジ日時 | 2024-10-14 01:51:15 |
合計ジャッジ時間 | 7,276 ms |
ジャッジサーバーID (参考情報) |
judge4 / judge3 |
(要ログイン)
ファイルパターン | 結果 |
---|---|
sample | AC * 3 |
other | AC * 12 |
ソースコード
public class Main {private static void solve() {int n = ni();int[] a = new int[n];a[0] = -1;for (int i = 0; i < n - 1; i ++) {a[i + 1] = ni();}int[][] g = parentToG(a);int[] ft = new int[n + 1];long ret = dfs(0, -1, g, ft);System.out.println(ret);}private static long dfs(int i, int j, int[][] g, int[] ft) {long ret = sumFenwick(ft, i);addFenwick(ft, i, 1);for (int to : g[i]) {if (to == j) continue;ret += dfs(to, i, g, ft);}addFenwick(ft, i, -1);return ret;}public static void addFenwick(int[] ft, int i, int v){if(v == 0 || i < 0)return;int n = ft.length;for(i++;i < n;i += i&-i)ft[i] += v;}public static int sumFenwick(int[] ft, int i){int sum = 0;for(i++;i > 0;i -= i&-i)sum += ft[i];return sum;}public static int[][] parentToG(int[] par){int n = par.length;int[] ct = new int[n];for(int i = 0;i < n;i++){if(par[i] >= 0){ct[i]++;ct[par[i]]++;}}int[][] g = new int[n][];for(int i = 0;i < n;i++){g[i] = new int[ct[i]];}for(int i = 0;i < n;i++){if(par[i] >= 0){g[par[i]][--ct[par[i]]] = i;g[i][--ct[i]] = par[i];}}return g;}public static void main(String[] args) {new Thread(null, new Runnable() {@Overridepublic void run() {long start = System.currentTimeMillis();String debug = args.length > 0 ? args[0] : null;if (debug != null) {try {is = java.nio.file.Files.newInputStream(java.nio.file.Paths.get(debug));} catch (Exception e) {throw new RuntimeException(e);}}reader = new java.io.BufferedReader(new java.io.InputStreamReader(is), 32768);solve();out.flush();tr((System.currentTimeMillis() - start) + "ms");}}, "", 64000000).start();}private static java.io.InputStream is = System.in;private static java.io.PrintWriter out = new java.io.PrintWriter(System.out);private static java.util.StringTokenizer tokenizer = null;private static java.io.BufferedReader reader;public static String next() {while (tokenizer == null || !tokenizer.hasMoreTokens()) {try {tokenizer = new java.util.StringTokenizer(reader.readLine());} catch (Exception e) {throw new RuntimeException(e);}}return tokenizer.nextToken();}private static double nd() {return Double.parseDouble(next());}private static long nl() {return Long.parseLong(next());}private static int[] na(int n) {int[] a = new int[n];for (int i = 0; i < n; i++)a[i] = ni();return a;}private static char[] ns() {return next().toCharArray();}private static long[] nal(int n) {long[] a = new long[n];for (int i = 0; i < n; i++)a[i] = nl();return a;}private static int[][] ntable(int n, int m) {int[][] table = new int[n][m];for (int i = 0; i < n; i++) {for (int j = 0; j < m; j++) {table[i][j] = ni();}}return table;}private static int[][] nlist(int n, int m) {int[][] table = new int[m][n];for (int i = 0; i < n; i++) {for (int j = 0; j < m; j++) {table[j][i] = ni();}}return table;}private static int ni() {return Integer.parseInt(next());}private static void tr(Object... o) {if (is != System.in)System.out.println(java.util.Arrays.deepToString(o));}}