几种排序算法之Java实现
问题描述：
排序int数组
分析：
目前只包括:
BubbleSort()
HeapSort()
InsertionSort()
MergeSort()
QuickSort()
ShellSort()
还有桶排序等未实现，待完善
代码实现：
package self.sort;
/**
* Created by bwhan on 4/28/15.
*/
public class BubbleSort {
public static void bubblesort(int[] a){
boolean done = false;
int size = a.length;
while(!done){
done = true;
for(int i = 0; i < size - 1; i++){
if(a[i] > a[i+1]){
done = false;
int tmp = a[i+1];
a[i+1] = a[i];
a[i] = tmp;
}
}
size--;
}
}
}
package self.sort;
/**
* Created by bwhan on 4/28/15.
*/
public class HeapSort {
public static void heapsort(int[] a){
for(int i = a.length/2; i >= 0; i--)
percDown(a, i, a.length);
for(int j = a.length - 1; j > 0; j--){
int tmp = a[0];
a[0] = a[j];
a[j] = tmp;
percDown(a, 0, j);
}
}
static int leftChild(int i){
return 2*i + 1;
}
static void percDown(int[] a, int i, int n){
int child;
int tmp;
for(tmp = a[i]; leftChild(i) < n; i = child){
child = leftChild(i);
if(child != n -1 && a[child] < a[child + 1])
child++;
if(tmp < a[child])
a[i] = a[child];
else
break;
}
a[i] = tmp;
}
}
package self.sort;
/**
* Created by bwhan on 4/28/15.
* Simple insertion sort.
* O(N^2)
**/
public class InsertionSort {
public static void insertionsort(int[] a){
for(int i = 1; i < a.length; i++){
int tmp = a[i];
int j;
for(j = i;j>0 && tmp < a[j-1];j--){
a[j] = a[j-1];
}
a[j] = tmp;
}
}
}
package self.sort;
/**
* Created by bwhan on 4/28/15.
*/
public class MergeSort {
public static void mergesort(int[] a){
int[] tmp = new int[a.length];
mergesort(a, tmp, 0, a.length - 1);
}
static void mergesort(int[] a, int[] tmp, int left, int right){
if(left < right){
int center = (left+right)/2;
mergesort(a, tmp, left, center);
mergesort(a, tmp, center + 1,right);
merge(a, tmp, left, center + 1, right);
}
}
static void merge(int[] a, int[] tmp, int leftPos, int rightPos, int rightEnd){
int leftEnd = rightPos - 1;
int tmpPos = leftPos;
int numElements = rightEnd - leftPos + 1;
while(leftPos <= leftEnd && rightPos <= rightEnd){
if(a[leftPos] <= a[rightPos])
tmp[tmpPos++] = a[leftPos++];
else
tmp[tmpPos++] = a[rightPos++];
}
while(leftPos <= leftEnd)
tmp[tmpPos++] = a[leftPos++];
while(rightPos <= rightEnd)
tmp[tmpPos++] = a[rightPos++];
for(int i = 0; i < numElements; i++, rightEnd--)
a[rightEnd] = tmp[rightEnd];
}
}
package self.sort;
import static self.sort.InsertionSort.insertionsort;
/**
* Created by bwhan on 4/29/15.
*/
public class QuickSort {
public static void quicksort(int[] a){
quicksort(a, 0, a.length - 1);
}
static final int median3(int[]a , int left, int right){
int center = (left + right)/2;
if(a[center] < a[left]){
int tmp = a[center];
a[left] = a[center];
a[center] = tmp;
}
if(a[right] < a[left]){
int tmp = a[right];
a[right] = a[left];
a[left] = tmp;
}
if(a[right] < a[center]){
int tmp = a[right];
a[right] = a[center];
a[center] = tmp;
}
int temp = a[center];
a[center] = a[right - 1];
a[right - 1] = temp;
return a[right - 1];
}
static void quicksort(int[] a, int left, int right){
if(left + 10 < right){
int pivot = median3(a, left, right);
int i = left, j = right - 1;
for(;;){
while(a[++i] < pivot){}
while(pivot < a[--j]){}
if(i < j){
int tmp = a[i];
a[i] = a[j];
a[j] = tmp;
} else
break;
}
int tmp = a[i];
a[i] = a[right - 1];
a[right - 1] = tmp;
quicksort(a, left, i - 1);
quicksort(a, i + 1, right);
}
else
insertionsort(a);
}
}
package self.sort;
/**
* Created by bwhan on 4/28/15.
*/
public class ShellSort {
public static void shellsort(int[] a) {
for(int gap = a.length/2; gap > 0; gap /= 2)
for(int i = gap; i < a.length; i++){
int tmp = a[i];
int j = i;
for(; j >= gap && tmp < a[j-gap]; j -= gap)
a[j] = a[j - gap];
a[j] = tmp;
}
}
}
package self.sort;
import self.tool.PrintData;
import static self.sort.BubbleSort.bubblesort;
import static self.sort.HeapSort.heapsort;
import static self.sort.InsertionSort.insertionsort;
import static self.sort.MergeSort.mergesort;
import static self.sort.QuickSort.quicksort;
import static self.sort.ShellSort.shellsort;
/**
* Created by bwhan on 4/28/15.
*/
public class SortTest {
public static void main(String[] args) {
int[] a = {9,3,4,5,1,6,8,2,12,14,22,18,3,11};
insertionsort(a);
PrintData.printarray(a);
int[] b = {9,3,4,5,1,6,8,2,12,14,22,18,3,11};
bubblesort(b);
PrintData.printarray(b);
int[] c = {9,3,4,5,1,6,8,2,12,14,22,18,3,11};
shellsort(c);
PrintData.printarray(c);
int[] d = {9,3,4,5,1,6,8,2,12,14,22,18,3,11};
heapsort(d);
PrintData.printarray(d);
int[] e = {9,3,4,5,1,6,8,2,12,14,22,18,3,11};
mergesort(e);
PrintData.printarray(e);
int[] f = {9,3,4,5,1,6,8,2,12,14,22,18,3,11};
quicksort(f);
PrintData.printarray(f);
}
}