5种java排序算法汇总工具类

网友投稿 206 2023-07-09


5种java排序算法汇总工具类

工具类简单明了地总结了java的快速排序,希尔排序,插入排序,堆排序,归并排序五种排序算法,代码中并没有对这几种排序算法的一个说明,关于思想部分希望在自行查阅相关说明,这里只是对这几种算法进行一个概括,以供大家使用。

public class Sort {

public static > void insertionSort(AnyType[] a) {

insertionSort(a, 0, a.length -http:// 1);

}

private static > void insertionSort(AnyType[] a, int left, int right) {

int j; // 记录第一个比tmp小的元素的后边一位的位置

for (int p = left; p <= right; p++) {

AnyType tmp = a[p];

for (j = p; j > left && tmp.compareTo(a[j - 1]) < 0; j--) {

a[j] = a[j - 1];

}

a[j] = tmp;

}

}

public static > void shellSort(AnyType[] arr) {

int j;

for (int gap = arr.length / 2; gap > 0; gap /= 2) {

for (int i = gap; i < arr.length; i++) {

AnyType tmp = arr[i];

for (j = i; j >= gap && tmp.compareTo(arr[j - gap]) < 0; j -= gap) {

arr[j] = arr[j - gap];

}

arr[j] = tmp;

}

}

}

private static int leftChild(int i) {

return i * 2 + 1;

}

private static > void perculateDown(AnyType[] arr, int i, int size) {

AnyType tmp = arr[i];

for (int child; (child = leftChild(i)) < size; i = child) {

if (child != size - 1 && arr[child].compareTo(arr[child + 1]) < 0) {

child++;

}

if (tmp.compareTo(arr[child]) < 0) {

arr[i] = arr[child];

} else {

break;

}

}

arr[i] = tmp;

}

public static > void heapSort(AnyType[] arr) {

for (int i = arr.length / 2; i >= 0; i--) {

perculateDown(arr, i, arr.length);

}

for (int i = arr.length - 1; i >= 0; i--) {

swapReferences(arr, 0, i);

perculateDown(arr, 0, i);

}

}

private static > void swapReferences(AnyType[] arr, int i, int j) {

AnyType tmp = arr[i];

arr[i] = arr[j];

arr[j] = tmp;

}

public static > void mergeSort(AnyType[] arr) {

AnyType[] tmp = ((AnyType[]) new Comparable[arr.length]);

mergeSort(arr, 0, arr.length - 1, tmp);

}

private static > void mergeSort(AnyType[] arr, int start, int end, AnyType[] tmp) {

if (start < end) {

int mid = (start + end) >> 1;

mergeSort(arr, start, mid, tmp);

mergeSort(arr, mid + 1, end, tmp);

merge(arr, start, mid, end, tmp);

}

}

private static > void merge(AnyType[] arr, int start, int mid, int end, AnyType[] tmp) {

int i = start, j = mid + 1, k = start;

while (i <= mid && j <= end) {

if (arr[i].compareTo(arr[j]) < 0) {

tmp[k++] = arr[i++];

} else {

tmp[k++] = arr[j++];

}

}

while (i <= midTrKyDwwFy) {

tmp[k++] = arr[i++];

}

while (j <= end) {

tmp[k++] = arr[j++];

}

for (int m = start; m <= end; m++) {

arr[m] = tmp[m];

}

}

public static > void quickSort(AnyType[] arr) {

quickSort(arr, 0, arr.length - 1)http://;

}

private static > void quickSort(AnyType[] arr, int left, int right) {

if (left + LENGTH_DIFF <= right) {

AnyType pivot = medium(arr, left, right);

int i = left, j = right;

while (true) {

while (arr[++i].compareTo(pivot) < 0);

while (arr[--j].compareTo(pivot) > 0);

if (i < j) {

swapReferences(arr, i, j);

} else {

break;

}

}

swapReferences(arr, i, right);

quickSort(arr, left, i - 1);

quickSort(arr, i + 1, right);

} else {

insertionSort(arr, left, right);

}

}

private static > AnyType medium(AnyType[] arr, int left,

int right) {

int center = (left + right) / 2;

if (arr[center].compareTo(arr[left]) < 0) {

swapReferences(arr, center, left);

}

if (arr[left].compareTo(arr[right]) > 0) {

swapReferences(arr, left, right);

}

if (arr[center].compareTo(arr[right]) < 0) {

swapReferences(arr, center, right);

}

return arr[right];

}

private final static int LENGTH_DIFF = 20;

}


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