1.排序基本知识
1.1初始排序
1.2十大排序算法
2.冒泡排序(Bubble Sort)
2.1Baseline
static void bubbleSort1(Integer[] array) { for (int end = array.length - 1; end > 0; end--) { for (int begin = 1; begin <= end; begin++) { if (array[begin] < array[begin - 1]) { int tmp = array[begin]; array[begin] = array[begin - 1]; array[begin - 1] = tmp; } } } }
2.2冒泡排序--优化1
static void bubbleSort2(Integer[] array) { for (int end = array.length - 1; end > 0; end--) { boolean sorted = true; for (int begin = 1; begin <= end; begin++) { if (array[begin] < array[begin - 1]) { int tmp = array[begin]; array[begin] = array[begin - 1]; array[begin - 1] = tmp; sorted = false; } } if (sorted) break; } }
2.3冒泡排序--优化2
static void bubbleSort3(Integer[] array) { for (int end = array.length - 1; end > 0; end--) { // sortedIndex的初始值在数组完全有序的时候有用 int sortedIndex = 1; for (int begin = 1; begin <= end; begin++) { if (array[begin] < array[begin - 1]) { int tmp = array[begin]; array[begin] = array[begin - 1]; array[begin - 1] = tmp; sortedIndex = begin; } } end = sortedIndex; } }
2.4排序算法的稳定性(Stability)
2.5原地算法(In-place Algorithm)
3.选择排序(Selection Sort)
3.1Baseline
static void selectionSort(Integer[] array) { for (int end = array.length - 1; end > 0; end--) { int maxIndex = 0; for (int begin = 1; begin <= end; begin++) { if (array[maxIndex] <= array[begin]) { maxIndex = begin; } } int tmp = array[maxIndex]; array[maxIndex] = array[end]; array[end] = tmp; } // 8 10 9 10 }
3.2堆排序(Heap Sort)
3.3堆排序实现
package com.mj.sort.cmp; import com.mj.sort.Sort; public class HeapSort<T extends Comparable<T>> extends Sort<T> { private int heapSize; @Override protected void sort() { // 原地建堆 heapSize = array.length; for (int i = (heapSize >> 1) - 1; i >= 0; i--) { siftDown(i); } while (heapSize > 1) { // 交换堆顶元素和尾部元素 swap(0, --heapSize); // 对0位置进行siftDown(恢复堆的性质) siftDown(0); } } private void siftDown(int index) { T element = array[index]; int half = heapSize >> 1; while (index < half) { // index必须是非叶子节点 // 默认是左边跟父节点比 int childIndex = (index << 1) + 1; T child = array[childIndex]; int rightIndex = childIndex + 1; // 右子节点比左子节点大 if (rightIndex < heapSize && cmp(array[rightIndex], child) > 0) { child = array[childIndex = rightIndex]; } // 大于等于子节点 if (cmp(element, child) >= 0) break; array[index] = child; index = childIndex; } array[index] = element; } }
原文地址:https://www.cnblogs.com/ggnbnb/p/12539761.html
时间: 2024-10-10 19:49:37