結果
| 問題 | No.2316 Freight Train |
| ユーザー |
 Asahi
|
| 提出日時 | 2023-05-26 22:42:50 |
| 言語 | Java (openjdk 23) |
| 結果 |
AC
|
| 実行時間 | 389 ms / 2,000 ms |
| コード長 | 6,910 bytes |
| コンパイル時間 | 2,485 ms |
| コンパイル使用メモリ | 80,280 KB |
| 実行使用メモリ | 51,380 KB |
| 最終ジャッジ日時 | 2024-12-25 09:04:02 |
| 合計ジャッジ時間 | 13,075 ms |
|
ジャッジサーバーID （参考情報） |
judge4 / judge5 |
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| ファイルパターン | 結果 |
|---|---|
| sample | AC * 3 |
| other | AC * 26 |
ソースコード
import java.util.*;
import java.io.*;
class Main{
void solve(PrintWriter out, In in) {
int n = in.nextInt() , Q = in.nextInt();
int [] par = in.IntArray(n);
DSU dsu = new DSU(n);
for(int i = 0 ; i < n ; i ++ ) {
if(par[i] == -1) continue;
dsu.unite(i,par[i]-1);
}
while(Q-->0) {
int a = in.nextInt() , b = in.nextInt();
a--;b--;
out.println(dsu.same(a,b)?"Yes":"No");
}
}
/* Library */
class DSU {
private int[] rank;
private int [] parent;
private int [] size;
DSU(int n) {
this.parent = new int[n];
this.rank = new int[n];
this.size = new int[n];
for (int i = 0 ; i < n; i ++ ) {
parent[i] = i;
rank[i] = 0;
size[i] = 1;
}
}
int groups() {
int count = 0;
for(int i = 0;i < parent.length ; i ++ ) {
if(i == find(i)) {
count++;
}
}
return count;
}
int size(int x){
return size[find(x)];
}
int find(int x) {
if (x == parent[x]) {
return x;
} else {
parent[x] = find(parent[x]);
return parent[x];
}
}
boolean same(int x, int y) {
return find(x) == find(y);
}
void unite(int x, int y) {
int xRoot = find(x);
int yRoot = find(y);
if (xRoot == yRoot) {
return;
}
if (rank[xRoot] > rank[yRoot]) {
parent[yRoot] = xRoot;
} else if (rank[xRoot] < rank[yRoot]) {
parent[xRoot] = yRoot;
} else {
parent[xRoot] = yRoot;
rank[xRoot]++;
size[yRoot] += size[xRoot];
}
}
}
/* ------- */
public static void main(String[] args) {
PrintWriter out = new PrintWriter(System.out);
In in = new In();
new Main().solve(out,in);
out.flush();
}
/* Const */
final long MOD7 = 1000000007; final long MOD9 = 998244353 ;
final int [] X4 = {0,1,0,-1}; final int [] Y4 = {-1,0,1,0};
final int [] X8 = {-1,-1,0,1,1,1,0,-1}; final int [] Y8 = {0,1,1,1,0,-1,-1,-1};
final int Inf = (int)1e9; final long Lnf = (long)1e18;
final String yes = "Yes"; final String no = "No";
/* ----- */
}
/* Class */
/* ----- */
class Pair{
private int first ;
private int second;
Pair(int first,int second) {
this.first = first;
this.second = second;
}
int first() { return this.first ; }
int second() { return this.second; }
@Override
public String toString(){ return first()+" = "+second(); }
}
class PairII {
private int first ;
private int second ;
private int third;
PairII(int first, int second, int third) {
this.first = first;
this.second = second;
this.third = third;
}
int first() { return this.first ; }
int second() { return this.second; }
int third() { return this.third ; }
@Override
public String toString(){ return first()+" = "+second()+" = "+third() ; }
}
class In{
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;
}
public boolean hasNext() {
while(hasNextByte() && !isPrintableChar(buffer[ptr])) {
ptr++;
}
return hasNextByte();
}
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();
}
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();
}
}
int nextInt() {
long nl = nextLong();
if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
return (int) nl;
}
double nextDouble() {
return Double.parseDouble(next());
}
int [] IntArray(int n) {
final int [] Array = new int [n];
for(int i = 0 ; i < n ; i ++ ) {
Array[i] = nextInt();
}
return Array;
}
int [][] IntArray(int n , int m) {
final int [][] Array = new int [n][m];
for(int i = 0 ; i < n ; i ++ ) {
Array[i] = IntArray(m);
}
return Array;
}
long [] LongArray(int n) {
final long [] Array = new long [n];
for(int i = 0 ; i < n ; i ++ ) {
Array[i] = nextLong();
}
return Array;
}
long [][] LongArray(int n , int m) {
final long [][] Array = new long [n][m];
for(int i = 0 ; i < n ; i ++ ) {
Array[i] = LongArray(m);
}
return Array;
}
String [] StringArray(int n) {
final String [] Array = new String [n];
for(int i = 0 ; i < n ; i ++ ) {
Array[i] = next();
}
return Array;
}
char [] CharArray(int n) {
final char [] Array = new char[n];
for(int i = 0 ; i < n ; i ++ ) {
Array[i] = next().charAt(0);
}
return Array;
}
char [][] CharArray(int n , int m) {
final char [][] Array = new char [n][m];
for(int i = 0 ; i < n ; i ++ ) {
Array[i] = next().toCharArray();
}
return Array;
}
}