結果

問題 No.763 Noelちゃんと木遊び
ユーザー 37zigen
提出日時 2018-12-23 10:43:54
言語 Java
(openjdk 23)
結果
AC  
実行時間 345 ms / 2,000 ms
コード長 2,935 bytes
コンパイル時間 3,045 ms
コンパイル使用メモリ 80,064 KB
実行使用メモリ 58,180 KB
最終ジャッジ日時 2024-09-25 10:30:23
合計ジャッジ時間 9,473 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
other AC * 21
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ソースコード

diff #
プレゼンテーションモードにする

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.NoSuchElementException;
class Main {
public static void main(String[] args) {
new Main().run();
}
void run() {
Scanner sc = new Scanner();
int N = sc.nextInt();
boolean[] ex = new boolean[N];
int[] deg = new int[N];
Arrays.fill(ex, true);
ArrayDeque<Integer> pd = new ArrayDeque<Integer>();
ArrayList<Integer>[] g = new ArrayList[N];
for (int i = 0; i < N; ++i) {
g[i] = new ArrayList<>();
}
for (int i = 0; i < N - 1; ++i) {
int u = sc.nextInt() - 1;
int v = sc.nextInt() - 1;
g[u].add(v);
g[v].add(u);
++deg[u];
++deg[v];
}
if (N == 1) {
System.out.println(1);
return;
}
for (int i = 0; i < N; ++i) {
if (deg[i] == 1)
pd.add(i);
}
int ans = 0;
while (!pd.isEmpty()) {
int u = pd.poll();
if (!ex[u])
continue;
for (int v : g[u]) {
if (!ex[v])
continue;
ex[v] = false;
for (int v2 : g[v]) {
if (!ex[v2])
continue;
--deg[v2];
if (deg[v2] == 0) {
++ans;
ex[v2] = false;
} else if (deg[v2] == 1) {
pd.add(v2);
}
}
}
}
System.out.println(ans);
}
void tr(Object... o) {
System.out.println(Arrays.deepToString(o));
}
}
class Scanner {
private final InputStream in = System.in;
private final byte[] buffer = new byte[1024];
private int ptr = 0;
private int buflen = 0;
private boolean hasNextByte() {
if (ptr < buflen) {
return true;
} else {
ptr = 0;
try {
buflen = in.read(buffer);
} catch (IOException e) {
e.printStackTrace();
}
if (buflen <= 0) {
return false;
}
}
return true;
}
private int readByte() {
if (hasNextByte())
return buffer[ptr++];
else
return -1;
}
private static boolean isPrintableChar(int c) {
return 33 <= c && c <= 126;
}
private void skipUnprintable() {
while (hasNextByte() && !isPrintableChar(buffer[ptr]))
ptr++;
}
public boolean hasNext() {
skipUnprintable();
return hasNextByte();
}
public String next() {
if (!hasNext())
throw new NoSuchElementException();
StringBuilder sb = new StringBuilder();
int b = readByte();
while (isPrintableChar(b)) {
sb.appendCodePoint(b);
b = readByte();
}
return sb.toString();
}
public long nextLong() {
if (!hasNext())
throw new NoSuchElementException();
long n = 0;
boolean minus = false;
int b = readByte();
if (b == '-') {
minus = true;
b = readByte();
}
if (b < '0' || '9' < b) {
throw new NumberFormatException();
}
while (true) {
if ('0' <= b && b <= '9') {
n *= 10;
n += b - '0';
} else if (b == -1 || !isPrintableChar(b)) {
return minus ? -n : n;
} else {
throw new NumberFormatException();
}
b = readByte();
}
}
public int nextInt() {
return (int) nextLong();
}
}
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