2022.8.28 小红书笔试
第一题 使用任意一种稳定排序即可
import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;
public class Q1 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int m = sc.nextInt();
int id = sc.nextInt();
int[][] records = new int[n][2];
for (int i = 0; i < n; i++) {
records[i][0] = i;
int ans = 0;
for (int j = 0; j < m; j++) {
ans += sc.nextInt();
}
records[i][1] = ans;
}
Arrays.sort(records, new Comparator<int[]>() { @Override public int compare(int[] o1, int[] o2) {
if (o1[1] != o2[1]){
return o2[1] - o1[1];
}
return o1[0] - o2[0];
}
});
for (int i = 0; i < n; i++) {
if(records[i][0] == id){
System.out.println(i);
break;
}
}
}
}
第二题 求满足乘积大于K的组合数
import java.util.Arrays;
import java.util.Scanner;
public class Q2 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
long k = sc.nextLong();
long[] power = new long[n];
for (int i = 0; i < n; i++) {
power[i] = sc.nextLong();
}
Arrays.sort(power);
long ans = 0;
for (int i = n - 1; i > 0; i--) {
long temp = ans;
for (int j = i - 1; j >= 0 ; j--) {
if (power[i] * power[j] < k){
break;
}
ans++;
}
if (ans == temp){
break;
}
}
System.out.println(ans);
}
}
第三题 一对一
import java.util.Arrays;
import java.util.Scanner;
public class Q3 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int ans = 0;
boolean[] vis = new boolean[n + 1];
int[][] friends = new int[n + 1][2];
int[] sum = new int[n + 1];
for (int i = 0; i <= n; i++) {
friends[i][0] = i;
}
int[][] graph = new int[n + 1][n + 1];
for (int i = 2; i <= n; i++) {
int j = sc.nextInt();
graph[i][j] = 1;
graph[j][i] = 1;
friends[i][1]++;
friends[j][1]++;
sum[i]++;
sum[j]++;
}
Arrays.sort(friends,(int[] o1, int[] o2) -> o1[1] - o2[1]);
for (int i = 1; i <= n ; i++) {
int index = friends[i][0];
if(!vis[index]){
vis[index] = true;
int min = Integer.MAX_VALUE;
int next = 0;
for (int j = 1; j <= n; j++) {
if (graph[index][j] == 1 && min > sum[j] && !vis[j]){
min = sum[j];
vis[next] = false;
next = j;
vis[next] = true;
}
}
if (next != 0){
ans++;
}
}
}
System.out.println(ans);
}
}
菜鸡纪念第一次提前交卷。
前两题都很简单，最后一题虽然A了，但代码写的很差，应该有更好的。
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