- package lhz.algorithm.chapter.five;
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http://mushiqianmeng.blog.51cto.com/3970029/734384
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- public class RandomArray {
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- private static int[] arrayOne = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
- 11, 12, 13 };
- private static int[] arrayTwo = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
- 11, 12, 13 };
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- public static void main(String[] args) {
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- permuteBySorting(arrayOne);
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- printArray(arrayOne);
- System.out.println("");
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- randomizeInPlace(arrayTwo);
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- printArray(arrayTwo);
- }
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- private static void permuteBySorting(int[] input) {
- int n = input.length;
- int[] p = new int[n];
- for (int i = 0; i < n; i++) {
- p[i] = randomValue(n);
- }
- mergeSort(input, p);
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-
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- }
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- private static void randomizeInPlace(int[] input) {
- int n = input.length;
- for (int i = 0; i < n; i++) {
- int index = (int) (Math.random() * (n - i - 1) + i);
- int temp = input[index];
- input[index] = input[i];
- input[i] = temp;
- }
- }
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- private static int randomValue(int n) {
- return (int) (Math.random() * (n * n * n - 1) + 1);
- }
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- private static int[] mergeSort(int[] array, int[] keyArray) {
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- if (array.length > 1) {
- int leftLength = array.length / 2;
- int rightLength = array.length - leftLength;
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- int[] left = new int[leftLength];
- int[] right = new int[rightLength];
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- int[] leftKey = new int[leftLength];
- int[] rightKey = new int[rightLength];
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- for (int i = 0; i < leftLength; i++) {
- left[i] = array[i];
- leftKey[i] = keyArray[i];
- }
- for (int i = 0; i < rightLength; i++) {
- right[i] = array[leftLength + i];
- rightKey[i] = keyArray[leftLength + i];
- }
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- left = mergeSort(left,leftKey);
- right = mergeSort(right,rightKey);
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- int i = 0;
- int j = 0;
- for (int k = 0; k < array.length; k++) {
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- if (i == leftLength && j < rightLength) {
- array[k] = right[j];
- j++;
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- } else if (i < leftLength && j == rightLength) {
- array[k] = left[i];
- i++;
-
- } else if (i < leftLength && j < rightLength) {
- if (leftKey[i] > rightKey[j]) {
- array[k] = right[j];
- j++;
- } else if (leftKey[i] < rightKey[j]){
- array[k] = left[i];
- i++;
- }
- }
- }
- }
- return array;
- }
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- private static void printArray(int[] array) {
- for (int i : array) {
- System.out.print(i + " ");
- }
- }
-
- }
本文转自mushiqianmeng 51CTO博客,原文链接:http://blog.51cto.com/mushiqianmeng/734384,如需转载请自行联系原作者