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package class01;
import java.util.Arrays;
public class Code04_SelectionSort {
public static void selectionSort(int[] arr) {
if (arr == null || arr.length < 2) {
return;
}
for (int i = 0; i < arr.length - 1; i++) {
int minIndex = i;
for (int j = i + 1; j < arr.length; j++) {
if(arr[j] < arr[minIndex]) {
minIndex = j;
}
}
swap(arr, i, minIndex);
}
}
public static void swap(int[] arr, int i, int j) {
int tmp = arr[i];
arr[i] = arr[j];
arr[j] = tmp;
}
// for test
public static void comparator(int[] arr) {
Arrays.sort(arr);
}
// for test
public static int[] generateRandomArray(int maxSize, int maxValue) {
// Math.random() [0,1)
// Math.random() * N [0,N)
// (int)(Math.random() * N) [0, N-1]
int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
for (int i = 0; i < arr.length; i++) {
// [-? , +?]
arr[i] = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
}
return arr;
}
// for test
public static int[] copyArray(int[] arr) {
if (arr == null) {
return null;
}
int[] res = new int[arr.length];
for (int i = 0; i < arr.length; i++) {
res[i] = arr[i];
}
return res;
}
// for test
public static boolean isEqual(int[] arr1, int[] arr2) {
if ((arr1 == null && arr2 != null) || (arr1 != null && arr2 == null)) {
return false;
}
if (arr1 == null && arr2 == null) {
return true;
}
if (arr1.length != arr2.length) {
return false;
}
for (int i = 0; i < arr1.length; i++) {
if (arr1[i] != arr2[i]) {
return false;
}
}
return true;
}
// for test
public static void printArray(int[] arr) {
if (arr == null) {
return;
}
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i] + " ");
}
System.out.println();
}
// for test
public static void main(String[] args) {
int testTime = 500000;
int maxSize = 100;
int maxValue = 100;
boolean succeed = true;
for (int i = 0; i < testTime; i++) {
int[] arr1 = generateRandomArray(maxSize, maxValue);
int[] arr2 = copyArray(arr1);
selectionSort(arr1);
comparator(arr2);
if (!isEqual(arr1, arr2)) {
succeed = false;
printArray(arr1);
printArray(arr2);
break;
}
}
System.out.println(succeed ? "Nice!" : "Fucking fucked!");
int[] arr = generateRandomArray(maxSize, maxValue);
printArray(arr);
selectionSort(arr);
printArray(arr);
}
}