AcWing 4303. 链表
原题链接
中等
作者:
没有你哪有我
,
2022-02-20 13:41:51
,
所有人可见
,
阅读 212
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int q = in.nextInt();
Map<String, String> map = new HashMap<>();
while (q -- > 0 ) {
String a = in.next();
String b = in.next();
if (map.containsKey(a)) {
String tail = map.get(a);
map.put(b, tail);
map.remove(a);
} else {
map.put(b, a);
}
}
System.out.println(map.size());
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println(entry.getValue() + " " + entry.getKey());
}
}
}