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Classrooms.java
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Classrooms.java
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import java.io.*;
import java.util.*;
class Interval implements Comparable<Interval>{
int s;
int e;
Interval(int s, int e) {
this.s = s;
this.e = e;
}
@Override
public int compareTo(Interval o) {
if (this.e == o.e) {
return this.s - o.s;
}
return this.e - o.e;
}
}
class Pair implements Comparable<Pair>{
int first;
int second;
Pair(int f, int s) {
this.first = f;
this.second = s;
}
@Override
public int compareTo(Pair o) {
if (this.first == o.first) {
return this.second - o.second;
}
return this.first - o.first;
}
}
public class Classrooms {
static class Reader {
final private int BUFFER_SIZE = 1 << 16;
private DataInputStream din;
private byte[] buffer;
private int bufferPointer, bytesRead;
public Reader() {
din = new DataInputStream(System.in);
buffer = new byte[BUFFER_SIZE];
bufferPointer = bytesRead = 0;
}
public int nextInt() throws IOException {
int ret = 0;
byte c = read();
while (c <= ' ') {
c = read();
}
boolean neg = (c == '-');
if (neg)
c = read();
do {
ret = ret * 10 + c - '0';
} while ((c = read()) >= '0' && c <= '9');
if (neg)
return -ret;
return ret;
}
private void fillBuffer() throws IOException {
bytesRead = din.read(buffer, bufferPointer = 0,
BUFFER_SIZE);
if (bytesRead == -1)
buffer[0] = -1;
}
private byte read() throws IOException {
if (bufferPointer == bytesRead)
fillBuffer();
return buffer[bufferPointer++];
}
}
public static void main(String[] args) throws IOException {
Reader sc = new Reader();
PrintWriter writer = new PrintWriter(System.out);
int n = sc.nextInt();
int k = sc.nextInt();
TreeSet<Pair> ts = new TreeSet<Pair>();
List<Interval> intervals = new ArrayList<Interval>();
while (n-- > 0)
intervals.add(new Interval(sc.nextInt(), sc.nextInt()));
Collections.sort(intervals);
for (int i = 0; i < k; i++)
ts.add(new Pair(0, i));
int ans = 0;
for (Interval interval : intervals) {
Pair available = ts.floor(new Pair(interval.s, k));
if (available != null) {
int id = available.second;
ts.remove(available);
ts.add(new Pair(interval.e + 1, id));
ans++;
}
}
writer.println(ans);
writer.flush();
}
}