演算法入門-堆排序
阿新 • • 發佈:2018-12-11
import java.util.Arrays; /** * 堆排序 * @author Administrator * */ public class Code05_heapSort { // 大根樹 public static void heapSort(int[] arr){ if(arr == null || arr.length < 2) return ; for(int i = 0; i < arr.length; i++){ heapInsert(arr, i); } int size = arr.length; swap(arr, 0, --size); while(size > 0){ heapify(arr, 0, size); swap(arr, 0, --size); } } public static void heapify(int[] arr, int index, int size){ int left = 2 * index + 1; while(left < size){ int largest = left + 1 < size && arr[left + 1] > arr[left] ? left + 1 : left; largest = arr[largest] > arr[index] ? largest : index; if(largest == index) break; swap(arr, largest, index); index = largest; left = 2 * index + 1; } } public static void heapInsert(int[] arr, int index){ while(arr[index] > arr[(index-1) / 2]){ swap(arr, index, (index-1) / 2); index = (index-1) / 2; } } public static void swap(int[] arr, int i, int j){ int temp; temp = arr[i]; arr[i] = arr[j]; arr[j] = temp; } // for test public static void comparator(int[] arr) { Arrays.sort(arr); } // for test public static int[] generateRandomArray(int maxSize, int maxValue) { 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); heapSort(arr1); comparator(arr2); if (!isEqual(arr1, arr2)) { succeed = false; break; } } System.out.println(succeed ? "Nice!" : "Fucking fucked!"); int[] arr = generateRandomArray(maxSize, maxValue); printArray(arr); heapSort(arr); printArray(arr); } }