冒泡排序:
package sort;
//冒泡
public class BubbleSort {
private int[] a;
public BubbleSort(int[] a) {
// TODO Auto-generated constructor stub
this.a = a;
}
//把小的冒泡到前面,即从小到大
public void sort() {
for (int i = 0;i < a.length;i++) {
for (int j = i+1;j < a.length;j++) {
if (a[i]>a[j]) {
int t = a[i];
a[i] = a[j];
a[j] = t;
}
}
}
}
public static void main(String[] args) {
int a[] = {5,6,4,3,8,6,4};
BubbleSort sort = new BubbleSort(a);
sort.sort();
for (int i:sort.a)
System.out.println(i);
}
}
插入排序:
package sort;
public class InsertSort {
private int[] a;
public InsertSort(int[] a) {
// TODO Auto-generated constructor stub
this.a = a;
}
//从小到大
public void sort() {
for (int i = 0;i < a.length;i++) {
for (int j = 0;j < i;j++) {
if (a[i]<a[j]) {
int t = a[i];
for (int k = i-1;k >= j;k--) {
a[k+1] = a[k];
}
a[j] = t;
}
}
}
}
public static void main(String[] args) {
int a[] = {5,6,4,3,8,6,4};
InsertSort sort = new InsertSort(a);
sort.sort();
for (int i:sort.a)
System.out.println(i);
}
}
归并排序:
package sort;
//归并
public class MergeSort {
private int a[];
private int length;
public MergeSort(int a[]) {
// TODO Auto-generated constructor stub
this.a = a;
this.length = a.length;
}
public void sort() {
MergeSort(0,length-1);
}
public void MergeSort(int m,int n) {
int mid = (m + n) / 2;
if (m < n) {
MergeSort(m, mid);
MergeSort(mid + 1, n);
Merge(m,mid,n);
}
}
public void Merge(int m, int mid, int n) {
System.out.println("Merge("+m+","+mid+","+n+")");
int p1 = m;
int p2 = mid + 1;
int temp[] = new int[n-m+1];
int p = 0;
if (m<n) {
while(p <= n - m) {
if (p1<=mid&&p2<=n) {
if (a[p1]<a[p2]) {
temp[p++] = a[p1++];
}else {
temp[p++] = a[p2++];
}
}
else {
if (p1>mid&&p2<=n) {
temp[p++] = a[p2++];
}
if (p2>n&&p1<=mid) {
temp[p++] = a[p1++];
}
}
}
for (int i=0;i<temp.length;i++) {
a[m + i] = temp[i];
}
}
}
public static void main(String[] args) {
int a[] = {5,6,4,3,8,6,4};
MergeSort sort = new MergeSort(a);
sort.sort();
for (int i:sort.a)
System.out.print(i+",");
}
}
package sort;
public class HeapSort {
private int a[];
private int length;
public HeapSort(int a[]) {
// TODO Auto-generated constructor stub
this.a = a;
this.length = a.length;
}
public void MaxHeap(int i) {
//int parent = (i+1)/2-1;
int left = 2*(i+1)-1;
int right = 2*(i+1);
if (left < length&&a[left] > a[right]&&a[left] > a[i]) {
int t = a[i];
a[i] = a[left];
a[left] = t;
MaxHeap(left);
}
else if (right < length&&a[left] < a[right]&&a[right] > a[i]) {
int t = a[i];
a[i] = a[right];
a[right] = t;
MaxHeap(right);
}
}
public void MakeMaxHeap() {
for (int i = length/2; i >= 0; i--) {
MaxHeap(i);
}
}
public void toLastPos(int i) {
int t = a[0];
a[0] = a[i];
a[i] = t;
length--;
}
public void sort() {
if (a == null || length <= 1) {
return;
}
MakeMaxHeap();
for (int i:a)
System.out.println("in:"+i);
//最大的被轮流挤进数组后面,最后变成由大到小排序好的数组
for(int i = length-1; i > 1; i--) {
toLastPos(i);
MaxHeap(0);
}
//当剩下两个节点时,这时如果把最大的数挤入数组中会导致还有一个节点没有被排序
//跳出循环后,剩下的两个节点执行一次MaxHeap(0)即完成了两个节点的排序
MaxHeap(0);
}
public static void main(String[] args) {
int a[] = {-3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
HeapSort sort = new HeapSort(a);
sort.sort();
for (int i:sort.a)
System.out.println(i);
}
}
快速排序:
package sort;
public class QuickSort {
private int[] a;
private int length;
public final static int Left = 0;
public final static int Right = 1;
public QuickSort(int a[]) {
// TODO Auto-generated constructor stub
this.a = a;
this.length = a.length;
}
public void QuickSort(int a[], int m, int n) {
if (n<=m) {
return;
}
int standard = choose(a, m, n);
int left = m;//左指针
int right = n;//右指针
int LeftOrRight = Left;//默认指针左移
while(left < right) {
//指针左移
if(LeftOrRight==Left) {
if (a[right] > standard) {
right--;
}
else if (a[right] <= standard&&a[left] >= standard) {
int t = a[right];
a[right] = a[left];
a[left] = t;
LeftOrRight = Right;
//这里是为了处理两边都等于基准值的情况,先移动一个指针后让下面的逻辑去处理,以免进入死循环
if (a[left] == standard&&a[right] == standard) {
right--;
}
}
else if (a[right] <= standard&&a[left] <= standard) {
LeftOrRight = Right;//左右都小于基准值时,改变指针移动方向
}
}
//指针右移
else {
if (a[left] < standard) {
left++;
}
else if (a[left] >= standard&&a[right] >= standard) {
LeftOrRight = Left;//左右都大于基准值时,改变指针移动方向
//这里是为了处理两边都等于基准值的情况,先移动一个指针后让下面的逻辑去处理,以免进入死循环
if (a[left] == standard&&a[right] == standard) {
left++;
}
}
else if (a[left] >= standard&&a[right] <= standard) {
int t = a[right];
a[right] = a[left];
a[left] = t;
LeftOrRight = Left;
}
}
}
//这里我增加了一段代码,由于在基准值的选择中会出现重复值,处理时找到基准值的最左边界和最右边界
//理解拙劣,只能采用这种方法。。
int times=0;
for (int i = 0; i <a.length;i++) {
if (a[i]==standard&×==0) {
left = i;
times++;
}
else if (a[i]==standard&×==0) {
right = i;
}
}
//System.out.println("m,n="+m+","+n+":standard="+standard);
QuickSort(a,m,left-1);
QuickSort(a,right+1,n);
}
public void sort() {
QuickSort(a,0,length-1);
}
public int choose(int[] a, int m, int n){
int standard = a[m];//选取第一个元素作为基准值
return standard;
}
public static void main(String[] args) {
int a[] = {5,6,4,3,8,6,4,5,234,2,35,23,5};
QuickSort sort = new QuickSort(a);
sort.sort();
for (int i:sort.a)
System.out.print(i+",");
}
}