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package class02;
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public class Code03_Comp {
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public static void selectionSort(int[] arr) {
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if (arr == null || arr.length < 2) {
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return;
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}
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for (int i = 0; i < arr.length - 1; i++) {
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int minIndex = i;
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for (int j = i + 1; j < arr.length; j++) {
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if (arr[j] < arr[minIndex]) {
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minIndex = j;
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}
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}
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swap(arr, i, minIndex);
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}
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}
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public static void swap(int[] arr, int i, int j) {
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int tmp = arr[i];
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arr[i] = arr[j];
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arr[j] = tmp;
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}
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public static void insertionSort(int[] arr) {
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if (arr == null || arr.length < 2) {
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return;
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}
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for (int i = 1; i < arr.length; i++) { // 0 ~ i 做到有序
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for (int j = i - 1; j >= 0 && arr[j] > arr[j + 1]; j--) {
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swap(arr, j, j + 1);
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}
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}
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}
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// 返回一个数组arr，arr长度[0,maxLen-1],arr中的每个值[0,maxValue-1]
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public static int[] lenRandomValueRandom(int maxLen, int maxValue) {
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int len = (int) (Math.random() * maxLen);
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int[] ans = new int[len];
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for (int i = 0; i < len; i++) {
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ans[i] = (int) (Math.random() * maxValue);
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}
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return ans;
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}
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public static int[] copyArray(int[] arr) {
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int[] ans = new int[arr.length];
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for (int i = 0; i < arr.length; i++) {
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ans[i] = arr[i];
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}
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return ans;
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}
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// arr1和arr2一定等长
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public static boolean isSorted(int[] arr) {
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if (arr.length < 2) {
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return true;
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}
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int max = arr[0];
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for (int i = 1; i < arr.length; i++) {
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if (max > arr[i]) {
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return false;
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}
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max = Math.max(max, arr[i]);
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}
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return true;
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}
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public static void main(String[] args) {
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int maxLen = 5;
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int maxValue = 1000;
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int testTime = 10000;
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for (int i = 0; i < testTime; i++) {
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int[] arr1 = lenRandomValueRandom(maxLen, maxValue);
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int[] tmp = copyArray(arr1);
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selectionSort(arr1);
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if (!isSorted(arr1)) {
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for (int j = 0; j < tmp.length; j++) {
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System.out.print(tmp[j] + " ");
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}
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System.out.println();
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System.out.println("选择排序错了！");
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break;
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}
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}
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}
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}
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