增加淘宝群内容,修改部分文件组织

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2021-10-13 17:26:45 +08:00
父節點 142168ae8e
當前提交 4152e12576
共有 646 個檔案被更改,包括 62259 行新增0 行删除

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<?xml version="1.0" encoding="UTF-8"?>
<classpath>
<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8"/>
<classpathentry kind="src" path="src"/>
<classpathentry kind="output" path="bin"/>
</classpath>

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<?xml version="1.0" encoding="UTF-8"?>
<projectDescription>
<name>01-复杂度</name>
<comment></comment>
<projects>
</projects>
<buildSpec>
<buildCommand>
<name>org.eclipse.jdt.core.javabuilder</name>
<arguments>
</arguments>
</buildCommand>
</buildSpec>
<natures>
<nature>org.eclipse.jdt.core.javanature</nature>
</natures>
</projectDescription>

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eclipse.preferences.version=1
org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
org.eclipse.jdt.core.compiler.compliance=1.8
org.eclipse.jdt.core.compiler.debug.lineNumber=generate
org.eclipse.jdt.core.compiler.debug.localVariable=generate
org.eclipse.jdt.core.compiler.debug.sourceFile=generate
org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
org.eclipse.jdt.core.compiler.source=1.8

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package com.mj;
public class Main {
/* 0 1 2 3 4 5
* 0 1 1 2 3 5 8 13 ....
*/
// O(2^n)
public static int fib1(int n) {
if (n <= 1) return n;
return fib1(n - 1) + fib1(n - 2);
}
// O(n)
public static int fib2(int n) {
if (n <= 1) return n;
int first = 0;
int second = 1;
for (int i = 0; i < n - 1; i++) {
int sum = first + second;
first = second;
second = sum;
}
return second;
}
public static int fib3(int n) {
if (n <= 1) return n;
int first = 0;
int second = 1;
while (n-- > 1) {
second += first;
first = second - first;
}
return second;
}
public static void main(String[] args) {
int n = 12;
System.out.println(fib2(n));
System.out.println(fib3(n));
// TimeTool.check("fib1", new Task() {
// public void execute() {
// System.out.println(fib1(n));
// }
// });
//
// TimeTool.check("fib2", new Task() {
// public void execute() {
// System.out.println(fib2(n));
// }
// });
}
public static void test1(int n) {
// 汇编指令
// 1
if (n > 10) {
System.out.println("n > 10");
} else if (n > 5) { // 2
System.out.println("n > 5");
} else {
System.out.println("n <= 5");
}
// 1 + 4 + 4 + 4
for (int i = 0; i < 4; i++) {
System.out.println("test");
}
// 140000
// O(1)
// O(1)
}
public static void test2(int n) {
// O(n)
// 1 + 3n
for (int i = 0; i < n; i++) {
System.out.println("test");
}
}
public static void test3(int n) {
// 1 + 2n + n * (1 + 3n)
// 1 + 2n + n + 3n^2
// 3n^2 + 3n + 1
// O(n^2)
// O(n)
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
System.out.println("test");
}
}
}
public static void test4(int n) {
// 1 + 2n + n * (1 + 45)
// 1 + 2n + 46n
// 48n + 1
// O(n)
for (int i = 0; i < n; i++) {
for (int j = 0; j < 15; j++) {
System.out.println("test");
}
}
}
public static void test5(int n) {
// 8 = 2^3
// 16 = 2^4
// 3 = log2(8)
// 4 = log2(16)
// 执行次数 = log2(n)
// O(logn)
while ((n = n / 2) > 0) {
System.out.println("test");
}
}
public static void test6(int n) {
// log5(n)
// O(logn)
while ((n = n / 5) > 0) {
System.out.println("test");
}
}
public static void test7(int n) {
// 1 + 2*log2(n) + log2(n) * (1 + 3n)
// 1 + 3*log2(n) + 2 * nlog2(n)
// O(nlogn)
for (int i = 1; i < n; i = i * 2) {
// 1 + 3n
for (int j = 0; j < n; j++) {
System.out.println("test");
}
}
}
public static void test10(int n) {
// O(n)
int a = 10;
int b = 20;
int c = a + b;
int[] array = new int[n];
for (int i = 0; i < array.length; i++) {
System.out.println(array[i] + c);
}
}
}

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package com.mj;
import java.text.SimpleDateFormat;
import java.util.Date;
public class Times {
private static final SimpleDateFormat fmt = new SimpleDateFormat("HH:mm:ss.SSS");
public interface Task {
void execute();
}
public static void test(String title, Task task) {
if (task == null) return;
title = (title == null) ? "" : ("" + title + "");
System.out.println(title);
System.out.println("开始:" + fmt.format(new Date()));
long begin = System.currentTimeMillis();
task.execute();
long end = System.currentTimeMillis();
System.out.println("结束:" + fmt.format(new Date()));
double delta = (end - begin) / 1000.0;
System.out.println("耗时:" + delta + "");
System.out.println("-------------------------------------");
}
}