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Commit 4cae8d8

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merge sort
1 parent 69e5941 commit 4cae8d8

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7 files changed

+649
-579
lines changed

7 files changed

+649
-579
lines changed

‎src/main/java/grey/algorithm/Code_0001_Gini.java‎

Lines changed: 47 additions & 46 deletions
Original file line numberDiff line numberDiff line change
@@ -9,51 +9,52 @@
99
//发生很多很多轮之后,这100人的社会财富分布很均匀吗?
1010
// 可以用基尼系数这个指标来做
1111
public class Code_0001_Gini {
12-
public static void main(String[] args) {
13-
System.out.println("一个社会的基尼系数是一个在0~1之间的小数");
14-
System.out.println("基尼系数为0代表所有人的财富完全一样");
15-
System.out.println("基尼系数为1代表有1个人掌握了全社会的财富");
16-
System.out.println("基尼系数越小,代表社会财富分布越均衡;越大则代表财富分布越不均衡");
17-
System.out.println("在2022年,世界各国的平均基尼系数为0.44");
18-
System.out.println("目前普遍认为,当基尼系数到达 0.5 时");
19-
System.out.println("就意味着社会贫富差距非常大,分布非常不均匀");
20-
System.out.println("社会可能会因此陷入危机,比如大量的犯罪或者经历社会动荡");
21-
System.out.println("测试开始");
22-
int num = 100;
23-
int round = 700000;
24-
System.out.println("人数 " + num);
25-
System.out.println("轮数 " + round);
26-
experiment(num, round);
27-
System.out.println("测试结束");
28-
}
2912

30-
public static void experiment(intnum, intround) {
31-
double[] people = newdouble[num];
32-
Arrays.fill(people, 100d);
33-
for (intn = 1; n <= round; n++) {
34-
for (inti = 0; i < num; i++) {
35-
intgiveTo = i;
36-
do {
37-
giveTo = (int) (Math.random() * num);
38-
} while (giveTo == i);
39-
if (people[i] > 0) {
40-
people[i]--;
41-
people[giveTo]++;
42-
}
43-
}
44-
}
45-
System.out.println("基尼系数为:" + gini(people));
46-
}
13+
public static void main(String[] args) {
14+
System.out.println("一个社会的基尼系数是一个在0~1之间的小数");
15+
System.out.println("基尼系数为0代表所有人的财富完全一样");
16+
System.out.println("基尼系数为1代表有1个人掌握了全社会的财富");
17+
System.out.println("基尼系数越小,代表社会财富分布越均衡;越大则代表财富分布越不均衡");
18+
System.out.println("在2022年,世界各国的平均基尼系数为0.44");
19+
System.out.println("目前普遍认为,当基尼系数到达 0.5 时");
20+
System.out.println("就意味着社会贫富差距非常大,分布非常不均匀");
21+
System.out.println("社会可能会因此陷入危机,比如大量的犯罪或者经历社会动荡");
22+
System.out.println("测试开始");
23+
intnum = 100;
24+
intround = 700000;
25+
System.out.println("人数 " + num);
26+
System.out.println("轮数 " + round);
27+
experiment(num, round);
28+
System.out.println("测试结束");
29+
}
4730

48-
public static double gini(double[] arr) {
49-
double sum = 0d;
50-
double sumAbs = 0d;
51-
for (int i = 0; i < arr.length; i++) {
52-
sum += arr[i];
53-
for (double v : arr) {
54-
sumAbs += Math.abs(arr[i] - v);
55-
}
56-
}
57-
return sumAbs / (sum * 2 * arr.length);
58-
}
59-
}
31+
public static void experiment(int num, int round) {
32+
double[] people = new double[num];
33+
Arrays.fill(people, 100d);
34+
for (int n = 1; n <= round; n++) {
35+
for (int i = 0; i < num; i++) {
36+
int giveTo = i;
37+
do {
38+
giveTo = (int) (Math.random() * num);
39+
} while (giveTo == i);
40+
if (people[i] > 0) {
41+
people[i]--;
42+
people[giveTo]++;
43+
}
44+
}
45+
}
46+
System.out.println("基尼系数为:" + gini(people));
47+
}
48+
49+
public static double gini(double[] arr) {
50+
double sum = 0d;
51+
double sumAbs = 0d;
52+
for (int i = 0; i < arr.length; i++) {
53+
sum += arr[i];
54+
for (double v : arr) {
55+
sumAbs += Math.abs(arr[i] - v);
56+
}
57+
}
58+
return sumAbs / (sum * 2 * arr.length);
59+
}
60+
}

‎src/main/java/grey/algorithm/Code_0003_BubbleSort.java‎

Lines changed: 73 additions & 72 deletions
Original file line numberDiff line numberDiff line change
@@ -5,82 +5,83 @@
55
//冒泡排序:0 ~ i范围上,相邻位置较大的数滚下去,最大值最终来到i位置,然后0~i-1范围上继续
66
//笔记:https://www.cnblogs.com/greyzeng/p/15186769.html
77
public class Code_0003_BubbleSort {
8-
public static void bubbleSort(int[] arr) {
9-
if (null == arr || arr.length <= 1) {
10-
return;
11-
}
12-
for (int i = arr.length - 1; i >= 0; i--) {
13-
// 每次搞定i位置的数
14-
for (int j = 0; j < i; j++) {
15-
if (arr[j] > arr[j + 1]) {
16-
swap(arr, j, j + 1);
17-
}
18-
}
19-
}
20-
}
218

22-
public static void swap(int[] arr, int i, int j) {
23-
if (null == arr || arr.length <= 1) {
24-
return;
25-
}
26-
int tmp = arr[i];
27-
arr[i] = arr[j];
28-
arr[j] = tmp;
29-
}
9+
public static void bubbleSort(int[] arr) {
10+
if (null == arr || arr.length <= 1) {
11+
return;
12+
}
13+
for (int i = arr.length - 1; i >= 0; i--) {
14+
// 每次搞定i位置的数
15+
for (int j = 0; j < i; j++) {
16+
if (arr[j] > arr[j + 1]) {
17+
swap(arr, j, j + 1);
18+
}
19+
}
20+
}
21+
}
3022

31-
public static void main(String[] args) {
23+
public static void swap(int[] arr, int i, int j) {
24+
if (null == arr || arr.length <= 1) {
25+
return;
26+
}
27+
int tmp = arr[i];
28+
arr[i] = arr[j];
29+
arr[j] = tmp;
30+
}
3231

33-
// 数组长度1~500,等概率随机
34-
int num = 500;
35-
// 每个值的大小在1~1024,等概率随机
36-
int value = 1024;
37-
// 测试次数
38-
int testTimes = 50000;
39-
System.out.println("测试开始");
40-
for (int i = 0; i < testTimes; i++) {
41-
int[] arr = generateArray(num, value);
42-
int[] copyArray = copyArray(arr);
43-
Arrays.sort(arr);
44-
bubbleSort(copyArray);
45-
if (!sameValue(arr, copyArray)) {
46-
System.out.println("出错了!");
47-
break;
48-
}
49-
}
50-
System.out.println("测试结束");
51-
}
32+
public static void main(String[] args) {
5233

53-
private static boolean sameValue(int[] arr1, int[] arr2) {
54-
if (null == arr1) {
55-
return null != arr2;
56-
}
57-
if (null == arr2) {
58-
return null != arr1;
59-
}
60-
if (arr1.length != arr2.length) {
61-
return false;
62-
}
63-
for (int i = 0; i < arr1.length; i++) {
64-
if (arr1[i] != arr2[i]) {
65-
return false;
66-
}
67-
}
68-
return true;
69-
}
34+
// 数组长度1~500,等概率随机
35+
int num = 500;
36+
// 每个值的大小在1~1024,等概率随机
37+
int value = 1024;
38+
// 测试次数
39+
int testTimes = 50000;
40+
System.out.println("测试开始");
41+
for (int i = 0; i < testTimes; i++) {
42+
int[] arr = generateArray(num, value);
43+
int[] copyArray = copyArray(arr);
44+
Arrays.sort(arr);
45+
bubbleSort(copyArray);
46+
if (!sameValue(arr, copyArray)) {
47+
System.out.println("出错了!");
48+
break;
49+
}
50+
}
51+
System.out.println("测试结束");
52+
}
7053

71-
private static int[] generateArray(int num, int value) {
72-
int[] arr = new int[(int) (Math.random() * num) + 1];
73-
for (int i = 0; i < arr.length; i++) {
74-
arr[i] = (int) (Math.random() * value) + 1;
75-
}
76-
return arr;
77-
}
54+
private static boolean sameValue(int[] arr1, int[] arr2) {
55+
if (null == arr1) {
56+
return null != arr2;
57+
}
58+
if (null == arr2) {
59+
return null != arr1;
60+
}
61+
if (arr1.length != arr2.length) {
62+
return false;
63+
}
64+
for (int i = 0; i < arr1.length; i++) {
65+
if (arr1[i] != arr2[i]) {
66+
return false;
67+
}
68+
}
69+
return true;
70+
}
7871

79-
private static int[] copyArray(int[] arr) {
80-
int[] copyArray = new int[arr.length];
81-
for (int i = 0; i < copyArray.length; i++) {
82-
copyArray[i] = arr[i];
83-
}
84-
return copyArray;
85-
}
72+
private static int[] generateArray(int num, int value) {
73+
int[] arr = new int[(int) (Math.random() * num) + 1];
74+
for (int i = 0; i < arr.length; i++) {
75+
arr[i] = (int) (Math.random() * value) + 1;
76+
}
77+
return arr;
78+
}
79+
80+
private static int[] copyArray(int[] arr) {
81+
int[] copyArray = new int[arr.length];
82+
for (int i = 0; i < copyArray.length; i++) {
83+
copyArray[i] = arr[i];
84+
}
85+
return copyArray;
86+
}
8687
}

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