算法
字符串翻转函数
strrev()函数用于char字符串数组，reverse()函数用于string类型的字符串。
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| #include <iostream>
#include <cstring>
using namespace std;
int main()
{
char s[]="hello";
strrev(s);
cout<<s<<endl;
return 0;
}
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main()
{
string s = "hello";
reverse(s.begin(),s.end());
cout<<s<<endl;
return 0;
}
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auto遍历
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| vector<int> res;
for(auto it : res)
cout << it;
|
java
CopyOnWriteArrayList
CopyOnWriteArrayList是线程安全的
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| CopyOnWriteArrayList<String> list = new CopyOnWriteArrayList<Stirng>();
|
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| package test;
import java.util.concurrent.CopyOnWriteArrayList;
public class TestCopyOnWriteArrayList {
public static void main(String[] args) {
CopyOnWriteArrayList<String> list = new CopyOnWriteArrayList<String>();
for (int i = 0; i < 10000; i++) {
new Thread(() -> {
list.add(Thread.currentThread().getName());
}).start();
}
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(list.size());
}
}
|
死锁
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| package test;
public class DeadLock {
public static void main(String[] args) {
Makeup g1 = new Makeup(0, "小明");
Makeup g2 = new Makeup(1 , "小红");
g1.start();
g2.start();
}
}
class Lipstick {
}
class Mirror {
}
class Makeup extends Thread {
static Lipstick lipstick = new Lipstick();
static Mirror mirror = new Mirror();
int choice;
String girlName;
public Makeup(int choice, String girlName) {
this.choice = choice;
this.girlName = girlName;
}
@Override
public void run() {
try {
makeup();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private void makeup() throws InterruptedException {
if(choice == 0) {
synchronized (lipstick) {
System.out.println(this.girlName + "获得口红锁");
Thread.sleep(1000);
}
// 分开锁
synchronized (mirror) {
System.out.println(this.girlName + "获得镜子锁");
}
}
else {
synchronized (mirror) {
System.out.println(this.girlName + "获得镜子锁");
Thread.sleep(2000);
}
synchronized (lipstick) {
System.out.println(this.girlName + "获得口红锁");
}
}
}
}
|
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