排序算法面试经典题:
1.快速排序:
package cn.lyx.test; /** * Created by lyx on 2018/5/21. */ public class QuickSort { public static void quickSort(int[] arr, int start, int end) { if (arr == null) return; if (start < end) { int mid = partirion(arr, start, end); quickSort(arr, start, mid - 1); quickSort(arr, mid + 1, end); } } public static void swap(int[] arr, int i, int j) { int temp = arr[i]; arr[i] = arr[j]; arr[j] = temp; } public static int partirion(int[] arr, int start, int end) { int pivote = arr[start]; while (start < end) { while (start < end && pivote < arr[end]) { end--; } swap(arr, start, end); while (start < end && pivote > arr[start]) { start++; } swap(arr, start, end); } return start; } public static void main(String[] args) { int[] arr = {5, 3, 4, 1, 2}; quickSort(arr, 0, arr.length - 1); for (int x : arr) { System.out.print(x+" "); } } }
2.冒泡排序:
package cn.lyx.test; /** * Created by lyx on 2018/5/21. */ public class BubleSort { public static void bubleSort(int[] arr) { boolean isSwapped = true; while (isSwapped) { isSwapped = false; for (int i = 0; i < arr.length; i++) { for (int j = 0; j < arr.length - i - 1; j++) { if (arr[j] > arr[j + 1]) { int temp = arr[j]; arr[j] = arr[j + 1]; arr[j + 1] = temp; isSwapped = true; } } } } } public static void main(String[] args) { int[] arr = {5, 1, 3, 4, 2}; bubleSort(arr); for (int x : arr) { System.out.print(x + " "); } } }