这是第一次笔试代码保留比较完整的，之前的笔试没保留代码，而且做的实在太差，只有看牛客大佬们帖子的份，这次回馈一下。
第一题 热点数据前十条 只通过了64%的测试用例
import javafx.util.Pair;
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String s = sc.nextLine();
int n = Integer.valueOf(s);
Map<Integer, Integer> map = new HashMap<>();
for(int i = 0; i < n; i++){
String s1 = sc.nextLine();
if(s1.equals("query")){
if(map.isEmpty()) System.out.println("null");
else{
Pair[] arr = new Pair[map.size()];
int index = 0;
for(int key : map.keySet()){
Pair<Integer,Integer> pair = new Pair<>(key, map.get(key));
arr[index++] = pair;
}
Arrays.sort(arr, (a, b) -> {
if(a.getValue() == b.getValue()){
return (int)a.getKey() - (int)b.getKey();
}else{
return (int)b.getValue() - (int)a.getValue();
}
});
int j = 1;
for(Pair pair : arr){
if(j > 10) break;
System.out.print(pair.getKey() + " ");
j++;
}
System.out.println();
}
}else{
String[] split = s1.split(" ");
int key = Integer.valueOf(split[1]);
int val = Integer.valueOf(split[2]);
map.put(key, map.getOrDefault(key, 0) + val);
}
}
}
}
第二题 战队
import java.util.*;
public class Main2 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int m = sc.nextInt();
int k = sc.nextInt();
long total_A = 0;
long total_B = 0;
for(int i = 0; i < n; i++){
int a = sc.nextInt();
int b = sc.nextInt();
if(b >= k) total_A += a * b;
}
for(int i = 0; i < m; i++){
int a = sc.nextInt();
int b = sc.nextInt();
if(b >= k) total_B += a * b;
}
System.out.print(total_A + " " + total_B);
if(total_A > total_B) System.out.println("A");
else System.out.println("B");
}
}
第三题 排车厢
import java.util.*;
public class Main3 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int N = Integer.valueOf(sc.nextLine());
List<List<Integer>> list = new ArrayList<>();
Map<String, List> map = new HashMap<>();
for(int i = 0; i < N; i++){
String s = sc.nextLine();
String[] split = s.split(" ");
int a = Integer.valueOf(split[0]);
if(a == 1){
int b = Integer.valueOf(split[1]);
String c = split[2];
if(map.containsKey(c)) map.get(c).add(b);
else{
List<Integer> arrayList = new ArrayList<>();
arrayList.add(b);
map.put(c, arrayList);
list.add(arrayList);
}
}else{
String b = split[1];
String c = split[2];
List<Integer> b_list = map.get(b);
List<Integer> c_list = map.get(c);
int index_b = 0;
int index_c = 0;
for(int j = 0; j < list.size(); j++){
if(list.get(j) == b_list) index_b = j;
if(list.get(j) == c_list) index_c = j;
}
list.remove(index_b);
list.add(index_b, c_list);
list.remove(index_c);
list.add(index_c, b_list);
}
}
for(List<Integer> list1 : list){
for(int num : list1){
System.out.print(num + " ");
}
}
}
}
第四题 树的不可到达节点
import java.util.*;
public class Main4 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int m = sc.nextInt();
int k = sc.nextInt();
List<Node> list = new ArrayList<>();
for(int i = 0; i < n; i++){
list.add(new Node());
}
for(int i = 0; i < m; i++){
int root = sc.nextInt() - 1;
int left = sc.nextInt() - 1;
int right = sc.nextInt() - 1;
list.get(root).left = list.get(left);
list.get(root).right = list.get(right);
}
for(int i = 0; i < n; i++){
list.get(i).val = sc.nextInt();
}
Node root = list.get(k - 1);
int ans = 0;
dfs(root, 1, Integer.MAX_VALUE);
for(Node node : list){
if(!node.flag){
ans += dfs1(node);
}
}
System.out.println(ans);
}
public static void dfs(Node node, int left, int right){
if(node == null) return;
if(left >= right) {
node.flag = false;
return;
}
dfs(node.left, left, Math.min(right, node.val));
dfs(node.right,Math.max(left, node.val), right);
}
public static int dfs1(Node node){
if(node == null) return 0;
return dfs1(node.left) + dfs1(node.right) + 1;
}
static class Node{
int val;
Node left;
Node right;
boolean flag = true;
}
}
第五题 扑克牌 没时间，骗分18%
import java.util.Scanner;
public class Main5 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int N = sc.nextInt();
for(int i = 0; i < N - 1; i++){
if(i % 2 == 0)System.out.println("Tuan");
else System.out.println("Draw");
}
System.out.println("Mei");
}
}
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