java实现各种基础排序（冒泡排序、快速排序、直接选择排序、堆排序、直接插入排序、归并排序）

前言

经过两个月的各种笔试面试，对各种基础排序算法原理了然于胸，用c闭着眼都能写出完美ac的代码来，今天刚看完java的数组，忍不住用java将各种排序实现一遍

注意，这篇文章只是为了锻炼java语法，不会深入讲各种排序原理，有兴趣的同学可以看我之前的博客，各自排序我都用c讲的非常清楚了

冒泡排序

public static void bubbleSort(int A[], int n) {int i, j;for (i = 0; i < n - 1; i ++) {for (j = 0; j < n - i - 1; j ++) {if (A[j] > A[j + 1]) {A[j] = A[j] ^ A[j + 1];A[j + 1] = A[j] ^ A[j + 1];A[j] = A[j] ^ A[j + 1];}}}}

直接插入排序

public static void insertSort(int A[], int n) {int i, j, tmp;for (i = 1; i < n; i++) {tmp = A[i];for (j = i - 1; j >= 0; j--) {if (A[j] > tmp) {A[j + 1] = A[j];} else {break;}}A[j + 1] = tmp;}}

直接选择排序

public static void selectSort(int A[], int n) {int i, j, loc;for (i = 0; i < n; i++) {loc = i;for (j = i + 1; j < n; j++) {if (A[j] < A[loc]) {loc = j;}}if (loc != i) {A[i] = A[i] ^ A[loc];A[loc] = A[i] ^ A[loc];A[i] = A[i] ^ A[loc];}}}

堆排序

/** * 堆排序（从小到大） *  * @param A * @param n */public static void heapSort(int A[], int n) {int tmp;// 构建大根堆buildMaxHeap(A, n);for (int j = n - 1; j >= 1; j--) {tmp = A[0];A[0] = A[j];A[j] = tmp;maxheapIfy(A, 0, j);}}/** * 构建大根堆 *  * @param A * @param n */private static void buildMaxHeap(int A[], int n) {for (int i = (n - 2) / 2; i >= 0; i--) {maxheapIfy(A, i, n);}}/** * 维护从下标i开始的最大堆 *  * @param A * @param i * @param n */private static void maxheapIfy(int A[], int i, int n) {int left, right, loc;while (i < n) {left = 2 * i + 1;right = 2 * i + 2;loc = i;if (left < n && A[left] > A[i]) {i = left;}if (right < n && A[right] > A[i]) {i = right;}if (loc != i) {A[i] = A[loc] ^ A[i];A[loc] = A[loc] ^ A[i];A[i] = A[loc] ^ A[i];} else {break;}}}

快速排序

public static void quickSort(int A[], int bt, int ed) {if (bt < ed) {int pivot = pivotPartition(A, bt, ed);quickSort(A, bt, pivot - 1);quickSort(A, pivot + 1, ed);}}private static void swapVar(int A[], int bt, int ed) {int mid = bt + (ed - bt) / 2;if (mid != bt) {A[bt] = A[bt] ^ A[mid];A[mid] = A[bt] ^ A[mid];A[bt] = A[bt] ^ A[mid];}}private static int pivotPartition(int A[], int bt, int ed) {// 取中间值作为stand，防止数组有序出现O(n^2)情况swapVar(A, bt, ed);int stand = A[bt];while (bt < ed) {while (bt < ed && A[ed] >= stand) {ed--;}if (bt < ed) {A[bt++] = A[ed];}while (bt < ed && A[bt] <= stand) {bt++;}if (bt < ed) {A[ed--] = A[bt];}}A[bt] = stand;return bt;}

归并排序

public static void mergeSort(int A[], int bt, int ed) {if (bt < ed) {int mid = bt + (ed - bt) / 2;mergeSort(A, bt, mid);mergeSort(A, mid + 1, ed);mergeArray(A, bt, mid, ed);}}private static void mergeArray(int A[], int bt, int mid, int ed) {int i, j, k, len = ed - bt + 1;int tmp[] = new int[len];for (i = bt, j = mid + 1, k = 0; i <= mid && j <= ed; k++) {if (A[i] <= A[j]) {tmp[k] = A[i++];} else {tmp[k] = A[j++];}}while (i <= mid) {tmp[k++] = A[i++];}while (j <= ed) {tmp[k++] = A[j++];}for (i = 0; i < k; i++) {A[bt + i] = tmp[i];}}

测试程序

import java.util.Scanner;public class JavaSort {public static void main(String args[]) {Scanner cin = new Scanner(System.in);int A[], n;while (cin.hasNext()) {n = cin.nextInt();A = new int[n];for (int i = 0; i < n; i++) {A[i] = cin.nextInt();}// bubbleSort(A, n);// insertSort(A, n);// selectSort(A, n);// heapSort(A, n);// quickSort(A, 0, n - 1);mergeSort(A, 0, n - 1);printArr(A);}}/** * 归并排序 *  * @param A * @param bt * @param ed */public static void mergeSort(int A[], int bt, int ed) {if (bt < ed) {int mid = bt + (ed - bt) / 2;mergeSort(A, bt, mid);mergeSort(A, mid + 1, ed);mergeArray(A, bt, mid, ed);}}/** * 合并数组 *  * @param A * @param bt * @param mid * @param ed */private static void mergeArray(int A[], int bt, int mid, int ed) {int i, j, k, len = ed - bt + 1;int tmp[] = new int[len];for (i = bt, j = mid + 1, k = 0; i <= mid && j <= ed; k++) {if (A[i] <= A[j]) {tmp[k] = A[i++];} else {tmp[k] = A[j++];}}while (i <= mid) {tmp[k++] = A[i++];}while (j <= ed) {tmp[k++] = A[j++];}for (i = 0; i < k; i++) {A[bt + i] = tmp[i];}}/** * 快速排序 *  * @param A * @param bt * @param ed */public static void quickSort(int A[], int bt, int ed) {if (bt < ed) {int pivot = pivotPartition(A, bt, ed);quickSort(A, bt, pivot - 1);quickSort(A, pivot + 1, ed);}}private static void swapVar(int A[], int bt, int ed) {int mid = bt + (ed - bt) / 2;if (mid != bt) {A[bt] = A[bt] ^ A[mid];A[mid] = A[bt] ^ A[mid];A[bt] = A[bt] ^ A[mid];}}/** * 快排寻找基准点位置 *  * @param A * @param bt * @param ed * @return */private static int pivotPartition(int A[], int bt, int ed) {// 取中间值作为stand，防止数组有序出现O(n^2)情况swapVar(A, bt, ed);int stand = A[bt];while (bt < ed) {while (bt < ed && A[ed] >= stand) {ed--;}if (bt < ed) {A[bt++] = A[ed];}while (bt < ed && A[bt] <= stand) {bt++;}if (bt < ed) {A[ed--] = A[bt];}}A[bt] = stand;return bt;}/** * 堆排序（从小到大） *  * @param A * @param n */public static void heapSort(int A[], int n) {int tmp;// 构建大根堆buildMaxHeap(A, n);for (int j = n - 1; j >= 1; j--) {tmp = A[0];A[0] = A[j];A[j] = tmp;maxheapIfy(A, 0, j);}}/** * 构建大根堆 *  * @param A * @param n */private static void buildMaxHeap(int A[], int n) {for (int i = (n - 2) / 2; i >= 0; i--) {maxheapIfy(A, i, n);}}/** * 维护从下标i开始的最大堆 *  * @param A * @param i * @param n */private static void maxheapIfy(int A[], int i, int n) {int left, right, loc;while (i < n) {left = 2 * i + 1;right = 2 * i + 2;loc = i;if (left < n && A[left] > A[i]) {i = left;}if (right < n && A[right] > A[i]) {i = right;}if (loc != i) {A[i] = A[loc] ^ A[i];A[loc] = A[loc] ^ A[i];A[i] = A[loc] ^ A[i];} else {break;}}}/** * 直接选择排序 *  * @param A * @param n */public static void selectSort(int A[], int n) {int i, j, loc;for (i = 0; i < n; i++) {loc = i;for (j = i + 1; j < n; j++) {if (A[j] < A[loc]) {loc = j;}}if (loc != i) {A[i] = A[i] ^ A[loc];A[loc] = A[i] ^ A[loc];A[i] = A[i] ^ A[loc];}}}/** * 直接插入排序 *  * @param A * @param n */public static void insertSort(int A[], int n) {int i, j, tmp;for (i = 1; i < n; i++) {tmp = A[i];for (j = i - 1; j >= 0; j--) {if (A[j] > tmp) {A[j + 1] = A[j];} else {break;}}A[j + 1] = tmp;}}/** * 冒泡排序 *  * @param A * @param n */public static void bubbleSort(int A[], int n) {int i, j;for (i = 0; i < n - 1; i++) {for (j = 0; j < n - i - 1; j++) {if (A[j] > A[j + 1]) {A[j] = A[j] ^ A[j + 1];A[j + 1] = A[j] ^ A[j + 1];A[j] = A[j] ^ A[j + 1];}}}}/** * 打印数组 *  * @param A */public static void printArr(int A[]) {for (int i = 0; i < A.length; i++) {if (i == A.length - 1) {System.out.printf("%d\n", A[i]);} else {System.out.printf("%d ", A[i]);}}}}