前两题想AC有难度没想到后两题都是水题。
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
class Main {
static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
static PrintWriter pw = new PrintWriter(System.out);
static int N = 10010;
static int a[] = new int[N];
public static void main(String[] args) throws IOException {
Arrays.fill(a, Integer.MAX_VALUE);
int n = Integer.parseInt(br.readLine());
int idx = 0;
for (int i = 0; i < n; i++) {
String s[] = br.readLine().split(" ");
for (int j = 0; j < s.length; j++) {
a[idx++] = Integer.parseInt(s[j]);
}
}
Arrays.sort(a);
for (int i = 1; i < idx; i++)
if (a[i] - a[i - 1] == 2)
pw.print(a[i] - 1 + " ");
else if (a[i] - a[i - 1] == 0)
pw.print(a[i] + " ");
pw.flush();
pw.close();
br.close();
}
}