AcWing 803. 区间合并
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.StreamTokenizer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public class Main {
static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
static PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
static StreamTokenizer sr = new StreamTokenizer(in);
static int n;
static List<int[]> list = new ArrayList<>();
public static void main(String[] args) throws IOException {
n = nextInt();
for (int i = 0, l, r; i < n; i++) {
l = nextInt();
r = nextInt();
list.add(new int[] { l, r });
}
Collections.sort(list, new Comparator<int[]>() {
public int compare(int[] o1, int[] o2) {
// TODO Auto-generated method stub
return o1[0] - o2[0];
}
});
int ans = 0;
int r = Integer.MIN_VALUE;
for (int[] arr : list) {
if(arr[0] > r) {
ans++;
}
r = Math.max(r, arr[1]);
}
out.println(ans);
out.flush();
}
private static int nextInt() throws IOException {
sr.nextToken();
return (int) sr.nval;
}
}