Java-Competitive-Programming/Algorithms/Matching.java at threads · joney000/Java-Competitive-Programming · GitHub

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import java.util.*;

import java.lang.*;

import java.io.*;

import java.math.*;

* Author : joney_000[let_me_start]

* Algorithm : Maximum matching for bipartite graph. Hopcroft-Karp algorithm in O(E * sqrt(V))

* Platform : https://www.facebook.com/hackercup

/* The Main Class */

public class A{

private InputStream inputStream ;

private OutputStream outputStream ;

private FastReader in ;

private PrintWriter out ;

Overhead [Additional Temporary Strorage] but provides memory reusibility for multiple test cases.

Size Limit : 10^5 + 4

private final int BUFFER = 100005;

private int tempints[] = new int[BUFFER];

private long templongs[] = new long[BUFFER];

private double tempdoubles[] = new double[BUFFER];

private char tempchars[] = new char[BUFFER];

private final long mod = 1000000000+7;

private final int INF = Integer.MAX_VALUE / 10;

private final long INF_L = Long.MAX_VALUE / 10;

public A(){}

public A(boolean stdIO)throws FileNotFoundException{

//stdIO = false;

if(stdIO){

inputStream = System.in;

outputStream = System.out;

}else{

inputStream = new FileInputStream("laundro_matt.txt");

outputStream = new FileOutputStream("output.txt");

}

in = new FastReader(inputStream);

out = new PrintWriter(outputStream);

}

final int MAXN1 = 50000;

final int MAXN2 = 50000;

final int MAXM = 150000;

int n1, n2, edges;

int last[] = new int[MAXN1];

int prev[] = new int[MAXM];

int head[] = new int[MAXM];

int matching[] = new int[MAXN2];

int dist[] = new int[MAXN1];

int Q[] = new int[MAXN1];

boolean used[] = new boolean[MAXN1];

boolean vis[] = new boolean[MAXN1];

void run()throws Exception{

int tests = i();

// once();

for(int t = 1 ; t<= tests ; t++){

n1 = i(); n2 = i();int e = i();

clear();

for(int i = 1 ; i<= e ;i++){

addEdge(i() , i());

}

long ans = maxMatching();

for(int i =0 ; i<= n2 ; i++)out.write("matching of n2["+i+"] ="+matching[i]+"\n");

out.write("Case #"+t+": "+ans+"\n");

}//end tests

}//end run

void once(){

}

void clear(){

edges = 0;

Arrays.fill(last, 0, n1, -1);

Arrays.fill(matching, 0, n2, 0);

Arrays.fill(head ,0, MAXM , 0);

Arrays.fill(prev ,0, MAXM , 0);

}

void addEdge(int u, int v) {

head[edges] = v;

prev[edges] = last[u];

last[u] = edges++;

}

void bfs() {

Arrays.fill(dist, 0, n1, -1);

int sizeQ = 0;

for (int u = 0; u < n1; ++u) {

if (!used[u]) {

Q[sizeQ++] = u;

dist[u] = 0;

}

for (int i = 0; i < sizeQ; i++) {

int u1 = Q[i];

for (int e = last[u1]; e >= 0; e = prev[e]) {

int u2 = matching[head[e]];

if (u2 >= 0 && dist[u2] < 0) {

dist[u2] = dist[u1] + 1;

Q[sizeQ++] = u2;

}

boolean dfs(int u1) {

vis[u1] = true;

for (int e = last[u1]; e >= 0; e = prev[e]) {

int v = head[e];

int u2 = matching[v];

if (u2 < 0 || !vis[u2] && dist[u2] == dist[u1] + 1 && dfs(u2)) {

matching[v] = u1;

used[u1] = true;

return true;

}

return false;

}

int maxMatching() {

Arrays.fill(used, 0, n1, false);

Arrays.fill(matching, 0, n2, -1);

for (int res = 0;;) {

bfs();

Arrays.fill(vis, 0, n1, false);

int f = 0;

for (int u = 0; u < n1; ++u)

if (!used[u] && dfs(u))

++f;

if (f <=0)

return res;

res += f;

}

//****************************** My Utilities ***********************//

void print_r(Object... o){

out.write("\n"+Arrays.deepToString(o)+"\n");

out.flush();

}

boolean isPrime(long n){

if(n==1)return false;

if(n<=3)return true;

if(n%2==0)return false;

for(int i=2 ;i <= Math.sqrt(n); i++){

if(n%i==0)return false;

}

return true;

}

// sieve

int[] primes(int n){ // for(int i=1;i<=arr.length-1;i++)out.write(""+arr[i]+" ");

boolean arr[] = new boolean[n+1];

Arrays.fill(arr,true);

arr[1]=false;

for(int i=2;i<=Math.sqrt(n);i++){

if(!arr[i])continue;

for(int j = 2*i ;j<=n;j+=i){

arr[j]=false;

}

LinkedList<Integer> ll = new LinkedList<Integer>();

for(int i=1;i<=n;i++){

if(arr[i])ll.add(i);

}

n = ll.size();

int primes[] = new int[n+1];

for(int i=1;i<=n;i++){

primes[i]=ll.removeFirst();

}

return primes;

}

long gcd(long a , long b){

if(b==0)return a;

return gcd(b , a%b);

}

long lcm(long a , long b){

if(a==0||b==0)return 0;

return (a*b)/gcd(a,b);

}

long mulmod(long a , long b ,long mod){

if(a==0||b==0)return 0;

if(b==1)return a;

long ans = mulmod(a,b/2,mod);

ans = (ans*2)% mod;

if(b%2==1)ans = (a + ans)% mod;

return ans;

}

long pow(long a , long b ,long mod){

if(b==0)return 1;

if(b==1)return a;

long ans = pow(a,b/2,mod);

ans = (ans * ans);

if(ans >= mod )ans %= mod;

if(b%2==1)ans = (a * ans);

if(ans >= mod )ans %= mod;

return ans;

}

// 20*20 nCr Pascal Table

long[][] ncrTable(){

long ncr[][] = new long[21][21];

for(int i=0 ;i<=20 ;i++){ncr[i][0]=1;ncr[i][i]=1;}

for(int j=0;j<=20 ;j++){

for(int i=j+1;i<= 20 ;i++){

ncr[i][j] = ncr[i-1][j]+ncr[i-1][j-1];

}

return ncr;

}

//*******************************I/O******************************//

int i()throws Exception{

//return Integer.parseInt(br.readLine().trim());

return in.nextInt();

}

int[] is(int n)throws Exception{

//int arr[] = new int[n+1];

for(int i=1 ; i <= n ;i++)tempints[i] = in.nextInt();

return tempints;

}

long l()throws Exception{

return in.nextLong();

}

long[] ls(int n)throws Exception{

for(int i=1 ; i <= n ;i++)templongs[i] = in.nextLong();

return templongs;

}

double d()throws Exception{

return in.nextDouble();

}

double[] ds(int n)throws Exception{

for(int i=1 ; i <= n ;i++)tempdoubles[i] = in.nextDouble();

return tempdoubles;

}

char c()throws Exception{

return in.nextCharacter();

}

char[] cs(int n)throws Exception{

for(int i=1 ; i <= n ;i++)tempchars[i] = in.nextCharacter();

return tempchars;

}

String s()throws Exception{

return in.nextLine();

}

BigInteger bi()throws Exception{

return in.nextBigInteger();

}

//***********************I/O ENDS ***********************//

//*********************** 0.3%f [precision]***********************//

/* roundoff upto 2 digits

double roundOff = Math.round(a * 100.0) / 100.0;

System.out.printf("%.2f", val);

print upto 2 digits after decimal

val = ((long)(val * 100.0))/100.0;

*/ private void closeResources(){

out.flush();

out.close();

return;

}

public static void main(String[] args) throws java.lang.Exception{

//let_me_start Shinch Returns

// Old Reader Writer

BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

BufferedWriter out=new BufferedWriter(new OutputStreamWriter(System.out));

BufferedReader br=new BufferedReader(new FileReader("input.txt"));

BufferedWriter out=new BufferedWriter(new FileWriter("output.txt"));

A driver = new A(true);

long start = System.currentTimeMillis();

driver.run();

long end = System.currentTimeMillis();

//out.write(" Total Time : "+(end - start)+"\n");

driver.closeResources();

return ;

}

class FastReader{

private boolean finished = false;

private InputStream stream;

private byte[] buf = new byte[4*1024];

private int curChar;

private int numChars;

private SpaceCharFilter filter;

public FastReader(InputStream stream){

this.stream = stream;

}

public int read(){

if (numChars == -1){

throw new InputMismatchException ();

}

if (curChar >= numChars){

curChar = 0;

try{

numChars = stream.read (buf);

} catch (IOException e){

throw new InputMismatchException ();

}

if (numChars <= 0){

return -1;

}

return buf[curChar++];

}

public int peek(){

if (numChars == -1){

return -1;

}

if (curChar >= numChars){

curChar = 0;

try{

numChars = stream.read (buf);

} catch (IOException e){

return -1;

}

if (numChars <= 0){

return -1;

}

return buf[curChar];

}

public int nextInt(){

int c = read ();

while (isSpaceChar (c))

c = read ();

int sgn = 1;

if (c == '-'){

sgn = -1;

c = read ();

}

int res = 0;

do{

if(c==','){

c = read();

}

if (c < '0' || c > '9'){

throw new InputMismatchException ();

}

res *= 10;

res += c - '0';

c = read ();

} while (!isSpaceChar (c));

return res * sgn;

}

public long nextLong(){

int c = read ();

while (isSpaceChar (c))

c = read ();

int sgn = 1;

if (c == '-'){

sgn = -1;

c = read ();

}

long res = 0;

do{

if (c < '0' || c > '9'){

throw new InputMismatchException ();

}

res *= 10;

res += c - '0';

c = read ();

} while (!isSpaceChar (c));

return res * sgn;

}

public String nextString(){

int c = read ();

while (isSpaceChar (c))

c = read ();

StringBuilder res = new StringBuilder ();

do{

res.appendCodePoint (c);

c = read ();

} while (!isSpaceChar (c));

return res.toString ();

}

public boolean isSpaceChar(int c){

if (filter != null){

return filter.isSpaceChar (c);

}

return isWhitespace (c);

}

public static boolean isWhitespace(int c){

return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;

}

private String readLine0(){

StringBuilder buf = new StringBuilder ();

int c = read ();

while (c != '\n' && c != -1){

if (c != '\r'){

buf.appendCodePoint (c);

}

c = read ();

}

return buf.toString ();

}

public String nextLine(){

String s = readLine0 ();

while (s.trim ().length () == 0)

s = readLine0 ();

return s;

}

public String nextLine(boolean ignoreEmptyLines){

if (ignoreEmptyLines){

return nextLine ();

}else{

return readLine0 ();

}

public BigInteger nextBigInteger(){

try{

return new BigInteger (nextString ());

} catch (NumberFormatException e){

throw new InputMismatchException ();

}

public char nextCharacter(){

int c = read ();

while (isSpaceChar (c))

c = read ();

return (char) c;

}

public double nextDouble(){

int c = read ();

while (isSpaceChar (c))

c = read ();

int sgn = 1;

if (c == '-'){

sgn = -1;

c = read ();

}

double res = 0;

while (!isSpaceChar (c) && c != '.'){

if (c == 'e' || c == 'E'){

return res * Math.pow (10, nextInt ());

}

if (c < '0' || c > '9'){

throw new InputMismatchException ();

}

res *= 10;

res += c - '0';

c = read ();

}

if (c == '.'){

c = read ();

double m = 1;

while (!isSpaceChar (c)){

if (c == 'e' || c == 'E'){

return res * Math.pow (10, nextInt ());

}

if (c < '0' || c > '9'){

throw new InputMismatchException ();

}

m /= 10;

res += (c - '0') * m;

c = read ();

}

return res * sgn;

}

public boolean isExhausted(){

int value;

while (isSpaceChar (value = peek ()) && value != -1)

read ();

return value == -1;

}

public String next(){

return nextString ();

}

public SpaceCharFilter getFilter(){

return filter;

}

public void setFilter(SpaceCharFilter filter){

this.filter = filter;

}

public interface SpaceCharFilter{

public boolean isSpaceChar(int ch);

}

/******************** Pair class ***********************/

class Pair implements Comparable<Pair>{

public long a;

public long b;

public Pair(){

this.a = 0L;

this.b = 0L;

}

public Pair(long a,long b){

this.a = a;

this.b = b;

}

public int compareTo(Pair p){

if(this.a + this.b < p.a + p.b)return -1;

else if(this.a + this.b > p.a + p.b )return 1;

else return 0;

}

public String toString(){

return "a="+this.a+" b="+this.b;

}

Java-Competitive-Programming/Algorithms/Matching.java at threads · joney000/Java-Competitive-Programming · GitHub

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