归并排序,基数排序
转载:http://blog.csdn.net/pzhtpf/article/details/7560312
7、归并排序
(1)基本排序:归并(Merge)排序法是将两个(或两个以上)有序表合并成一个新的有序表,即把待排序序列分为若干个子序列,每个子序列是有序的。然后再把有序子序列合并为整体有序序列。
(2)实例:
(3)用java实现
- import java.util.Arrays;
- public class mergingSort {
- int a[]={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51};
- public mergingSort(){
- sort(a,0,a.length-1);
- for(int i=0;i<a.length;i++)
- System.out.println(a[i]);
- }
- public void sort(int[] data, int left, int right) {
- // TODO Auto-generated method stub
- if(left<right){
- //找出中间索引
- int center=(left+right)/2;
- //对左边数组进行递归
- sort(data,left,center);
- //对右边数组进行递归
- sort(data,center+1,right);
- //合并
- merge(data,left,center,right);
- }
- }
- public void merge(int[] data, int left, int center, int right) {
- // TODO Auto-generated method stub
- int [] tmpArr=new int[data.length];
- int mid=center+1;
- //third记录中间数组的索引
- int third=left;
- int tmp=left;
- while(left<=center&&mid<=right){
- //从两个数组中取出最小的放入中间数组
- if(data[left]<=data[mid]){
- tmpArr[third++]=data[left++];
- }else{
- tmpArr[third++]=data[mid++];
- }
- }
- //剩余部分依次放入中间数组
- while(mid<=right){
- tmpArr[third++]=data[mid++];
- }
- while(left<=center){
- tmpArr[third++]=data[left++];
- }
- //将中间数组中的内容复制回原数组
- while(tmp<=right){
- data[tmp]=tmpArr[tmp++];
- }
- System.out.println(Arrays.toString(data));
- }
- }
8、基数排序
(1)基本思想:将所有待比较数值(正整数)统一为同样的数位长度,数位较短的数前面补零。然后,从最低位开始,依次进行一次排序。这样从最低位排序一直到最高位排序完成以后,数列就变成一个有序序列。
(2)实例:
(3)用java实现
- import java.util.ArrayList;
- import java.util.List;
- public class radixSort {
- int a[]={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,101,56,17,18,23,34,15,35,25,53,51};
- public 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++;
- }
- }
- }
- }
- }