标签：算法 排序 Algorithms
public class SortDemo { // private static long[] arr = {6,5,2,7,1,8,4,3}; private static long[] arr = {1,2,3,4,5,6,7,8}; private static int count = 0; /** * 冒泡排序 * O(n2) */ public static void bubble(){ long temp = Long.MIN_VALUE; int len = arr.length; for(int j = 0;j<len;j++){ for(int i = 0;i<len-1;i++){ if(arr[i]>arr[i+1]){ temp = arr[i+1]; arr[i+1] = arr[i]; arr[i] = temp; } } } } /** * 选择排序 * O(n2) */ public static void select(){ int len = arr.length; long temp = Long.MIN_VALUE; int index = 0; for(int j = 0;j<len;j++){ index = j; for(int i = j;i<len;i++){ if(arr[i]<arr[index]){ index = i; } } temp = arr[j]; arr[j] = arr[index]; arr[index] = temp; print(); } } /** * 插入排序 * O(n2) */ public static void insert(){ int len = arr.length; long temp; for(int i=1;i<len;i++){ int j = i-1; temp = arr[i]; while(j>=0 && temp<arr[j]){ arr[j+1] = arr[j]; j--; } arr[j+1] = temp; print(); } } /** * 快速排序 * O(N*longN) */ public static void quick(){ quick(arr); print(); } private static long[] quick(long[] a){ if(a.length<=1)return a; long temp = 0; int index = 0; for(int i = 0;i<a.length-1;i++){ if(a[i]<a[a.length-1]){ temp = a[i]; a[i] = a[index]; a[index++] = temp; } } temp = a[a.length-1]; a[a.length-1] = a[index]; a[index] = temp; if(index==0)return a; long[] temp1 = new long[index]; long[] temp2 = new long[a.length-index-1]; System.arraycopy(a, 0, temp1, 0, index); System.arraycopy(a, index+1, temp2, 0, a.length-index-1); System.arraycopy(quick(temp1), 0, a, 0, index); System.arraycopy(quick(temp2), 0, a, index+1, a.length-index-1); return a; } /** * 归并排序 * O(N*longN) */ public static void merge (){ arr = merge(arr); print(); } private static long[] merge(long[] a){ long[] c = new long[a.length]; int mid = a.length/2; long[] temp1 = new long[mid]; long[] temp2 = new long[a.length-mid]; if(mid>1){ System.arraycopy(a, 0, temp1, 0, mid); System.arraycopy(a, mid, temp2, 0, a.length-mid); temp1 = merge(temp1); temp2 = merge(temp2); System.arraycopy(temp1, 0, a, 0, mid); System.arraycopy(temp2, 0, a, mid, a.length-mid); } int i=0,j=mid,index=0; while(i<mid && j<a.length && index<a.length-1){ if(a[i]<a[j]){ c[index++] = a[i++]; }else{ c[index++] = a[j++]; } } while(index<a.length && i<mid){ c[index++] = a[i++]; } while(index<a.length && j<a.length){ c[index++] = a[j++]; } return c; } public static void print(){ for(long v:arr){ System.out.print(v); } System.out.println(); } public static void main(String[] args) { quick(); } }标签：算法 排序 Algorithms
原文地址：http://blog.51cto.com/12336708/2104475
