直接插入排序
//直接插入排序 public int[] insertSort(int[] a) { for (int i = 1; i < a.length; i++) { int j = i - 1; for (; j >= 0 && a[j] > a[i]; j--) { a[j + 1] = a[j];//往后移 } a[j + 1] = a[i]; } return a; }
希尔排序
//希尔排序 public int[] shellSort(int[] a) { int n = a.length; int gap = n;//数组数 while (gap > 0) { gap = gap / 2;//将数组缩小一半 for (int x = 0; x < gap; x++) {//将每组数进行直接插入排序 //直接插入排序 for (int i = x + gap; i < n; i += gap) { int j = i - gap; for (; j >= 0 && a[j] > a[i]; j -= gap) { a[j + gap] = a[j]; } a[j + gap] = a[i]; } } } return a; }
简单选择排序
//简单选择排序 public int[] simpleSort(int[] a) { int n = a.length; for (int i = 0; i < n; i++) { for (int j = i + 1; j <= n; j++) { if (a[j] < a[i]) { int temp = a[i]; a[i] = a[j]; a[j] = temp; } } } return a; }
堆排序
//堆排序 public void heapSort(int[] a) { System.out.println("开始排序"); int arrayLength = a.length; //循环建堆,每次把最大值放在最后,不参与下一次的建堆 for (int i = 0; i < arrayLength - 1; i++) { //建堆 buildMaxHeap(a, arrayLength - 1 - i); //交换堆顶和最后一个元素 swap(a, 0, arrayLength - 1 - i); System.out.println(Arrays.toString(a)); } } private void swap(int[] data, int i, int j) { int tmp = data[i]; data[i] = data[j]; data[j] = tmp; } //对data数组从0到lastIndex建大顶堆 private void buildMaxHeap(int[] data, int lastIndex) { //从lastIndex处节点(最后一个节点)的父节点开始,(lastIndex - 1) / 2为节点数 for (int i = (lastIndex - 1) / 2; i >= 0; i--) { //k保存正在判断的节点 int k = i; //如果当前k节点的子节点存在,把堆中最大的数放在对顶 while (k * 2 + 1 <= lastIndex) { //k节点的左子节点的索引 int biggerIndex = 2 * k + 1; //如果biggerIndex小于lastIndex,即biggerIndex+1代表的k节点的右子节点存在 if (biggerIndex < lastIndex) { //若果右子节点的值较大 if (data[biggerIndex] < data[biggerIndex + 1]) { //biggerIndex总是记录较大子节点的索引 biggerIndex++; } } //如果k节点的值小于其较大的子节点的值 if (data[k] < data[biggerIndex]) { //交换他们 swap(data, k, biggerIndex); //将biggerIndex赋予k,开始while循环的下一次循环,重新保证k节点的值大于其左右子节点的值 k = biggerIndex; } else { break; } } } }
冒泡排序
//冒泡排序 public int[] bubbleSort(int[] a) { int temp = 0; for (int i = 0; i < a.length - 1; i++) { for (int j = 0; j < a.length - 1 - i; j++) { if (a[j] > a[j + 1]) { temp = a[j]; a[j] = a[j + 1]; a[j + 1] = temp; } } } return a; }
快速排序
//快速排序 public void quickSort() { quick(a); for (int i = 0; i < a.length; i++) { System.out.println(a[i]); } } public int getMiddle(int[] list, int low, int high) { int tmp = list[low]; //数组的第一个作为中轴 while (low < high) { while (low < high && list[high] >= tmp) { high--; } list[low] = list[high]; //比中轴小的记录移到低端 while (low < high && list[low] <= tmp) { low++; } list[high] = list[low]; //比中轴大的记录移到高端 } list[low] = tmp; //中轴记录到尾 return low; //返回中轴的位置 } public void _quickSort(int[] list, int low, int high) { if (low < high) { int middle = getMiddle(list, low, high); //将list数组进行一分为二 _quickSort(list, low, middle - 1); //对低字表进行递归排序 _quickSort(list, middle + 1, high); //对高字表进行递归排序 } } public void quick(int[] a2) { if (a2.length > 0) { //查看数组是否为空 _quickSort(a2, 0, a2.length - 1); } }
归并排序
//归并排序 public void mergeSort(int[] arr) { int[] temp = new int[arr.length]; internalMergeSort(arr, temp, 0, arr.length - 1); } private void internalMergeSort(int[] a, int[] b, int left, int right) { //当left==right的时,已经不需要再划分了 if (left < right) { int middle = (left + right) / 2; internalMergeSort(a, b, left, middle);//左子数组 internalMergeSort(a, b, middle + 1, right);//右子数组 mergeSortedArray(a, b, left, middle, right);//合并两个子数组 } } // 合并两个有序子序列 arr[left, ..., middle] 和 arr[middle+1, ..., right],temp是辅助数组。 private void mergeSortedArray(int arr[], int temp[], int left, int middle, int right) { int i = left; int j = middle + 1; int k = 0; //从两个数组中取出最小的放入临时数组 while (i <= middle && j <= right) { if (arr[i] <= arr[j]) { temp[k++] = arr[i++]; } else { temp[k++] = arr[j++]; } } //将左数组剩下的数据复制到临时数组 while (i <= middle) { temp[k++] = arr[i++]; } //将右数组剩下的数据复制到临时数组 while (j <= right) { temp[k++] = arr[j++]; } //把数据复制回原数组 for (i = 0; i < k; ++i) { arr[left + i] = temp[i]; } }
基数排序
//基数排序 public void radixSort() { sort(a); for (int i = 0; i < a.length; i++) { System.out.println(a[i]); } } public void sort(int[] array) { //首先确定排序的趟数; int max = array[0]; for (int i = 1; i < array.length; i++) { if (array[i] > max) { max = array[i]; } } int time = 0; //判断位数; while (max > 0) { max /= 10; time++; } //建立10个队列; List<ArrayList> queue = new ArrayList<ArrayList>(); for (int i = 0; i < 10; i++) { ArrayList<Integer> queue1 = new ArrayList<Integer>(); queue.add(queue1); } //进行time次分配和收集; for (int i = 0; i < time; i++) { //分配数组元素; for (int j = 0; j < array.length; j++) { //得到数字的第time+1位数; int x = array[j] % (int) Math.pow(10, i + 1) / (int) Math.pow(10, i); ArrayList<Integer> queue2 = queue.get(x); queue2.add(array[j]); queue.set(x, queue2); } int count = 0;//元素计数器; //收集队列元素; for (int k = 0; k < 10; k++) { while (queue.get(k).size() > 0) { ArrayList<Integer> queue3 = queue.get(k); array[count] = queue3.get(0); queue3.remove(0); count++; } } } }
原文链接: Java常用排序算法/程序员必须掌握的8大排序算法
时间: 2024-10-07 14:23:44