2021/8/22 爱奇艺笔试 全AC
1、sql 略
2、峰值-谷值问题
import java.util.Scanner;
public class Main1 {
public static void main(String[] args) {
Scanner scanner=new Scanner(System.in);
while(scanner.hasNext()){
String[] line=scanner.nextLine().split(",");
int n=line.length;
int[] nums=new int[n];
for(int i=0;i<n;i++){
nums[i]=Integer.parseInt(line[i]);
}
solve(n,nums);
}
}
private static void solve(int n, int[] nums) {
int peek=Math.max(nums[0],nums[1]);
int down=Math.min(nums[0],nums[1]);
int ans=peek-down;
for(int i=2;i<n;i++){
if((nums[i]-nums[i-1])*(nums[i-1]-nums[i-2])>=0){
if(nums[i]>nums[i-1]){
peek=nums[i];
}else{
down=nums[i];
}
}else{
if(nums[i]>nums[i-1]){
down=nums[i-1];
peek=nums[i];
}else{
down=nums[i];
peek=nums[i-1];
}
}
ans=Math.max(peek-down,ans);
}
System.out.println(ans);
}
}
3、n皇后 import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Main2 {
public static void main(String[] args) {
Scanner scanner=new Scanner(System.in);
int n=Integer.parseInt(scanner.nextLine());
boolean[] col=new boolean[n];
boolean[] line1=new boolean[2*n-1];
boolean[] line2=new boolean[2*n-1];
List<String> ans=new ArrayList<>();
dfs(ans,n,new ArrayList<Integer>(),0,col,line1,line2);
System.out.print("[");
for(int i=0;i<ans.size();i++){
System.out.print(ans.get(i));
if(i!=ans.size()-1){
System.out.print(", ");
}
}
System.out.print("]");
}
private static void dfs(List<String> ans,int n, ArrayList<Integer> path, int cnt,boolean[] col,boolean[] line1,boolean[] line2) {
if(cnt==n){
//
String s="[";
for(int i=0;i<n;i++){
Integer index = path.get(i);
for(int j=0;j<n;j++){
if(j==index){
s+="Q";
}else{
s+=".";
}
}
if(i!=n-1){
s+=", ";
}
}
s+="]";
ans.add(s);
return;
}
for(int i=0;i<n;i++){
if(col[i]) continue;
if(line1[i+cnt]) continue;
if(line2[cnt-i+n-1]) continue;
col[i]=true;
line1[i+cnt]=true;
line2[cnt-i+n-1]=true;
path.add(i);
dfs(ans,n,path,cnt+1,col,line1,line2);
col[i]=false;
line1[i+cnt]=false;
line2[cnt-i+n-1]=false;
path.remove(path.size()-1);
}
}
}
4、多发问题 import java.util.Scanner;
import java.util.concurrent.Semaphore;
import java.util.function.IntConsumer;
public class Main3 {
public static void main(String[] args) {
final Scanner reader = new Scanner(System.in);
int n = reader.nextInt();
ZeroEvenOdd zeroEvenOdd = new ZeroEvenOdd(n);
new Thread(() -> {
try {
zeroEvenOdd.printZero(System.out::print);
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
new Thread(() -> {
try {
zeroEvenOdd.printEven(System.out::print);
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
new Thread(() -> {
try {
zeroEvenOdd.printOdd(System.out::print);
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
}
}
class ZeroEvenOdd {
private int n;
Semaphore semaphore1=new Semaphore(0);
Semaphore semaphore2=new Semaphore(0);
Semaphore semaphore3=new Semaphore(0);
public ZeroEvenOdd(int n) {
this.n = n;
}
// printNumber.accept(x) outputs "x", where x is an integer.
public void printZero(IntConsumer printNumber) throws InterruptedException {
for(int i=0;i<n;i++){
if(i!=0){
semaphore1.acquire();
}
printNumber.accept(0);
if(i%2==0){
semaphore3.release();
} else{
semaphore2.release();
}
}
}
public void printEven(IntConsumer printNumber) throws InterruptedException {
for(int i=0;i<n;i++){
if((i+1)%2==0){
semaphore2.acquire();
printNumber.accept(i+1);
semaphore1.release();
}
}
}
public void printOdd(IntConsumer printNumber) throws InterruptedException {
for(int i=0;i<n;i++){
if((i+1)%2==1){
semaphore3.acquire();
printNumber.accept(i+1);
semaphore1.release();
}
}
}
} 