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 <anytype extends comparable<? super anytype>> void insertionsort(anytype[] a) {
  insertionsort(a, 0, a.length - 1);
 }
 
 private static <anytype extends comparable<? super anytype>> 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 <anytype extends comparable<? super anytype>> 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 <anytype extends comparable<? super anytype>> 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 <anytype extends comparable<? super anytype>> 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 <anytype extends comparable<? super anytype>> void swapreferences(anytype[] arr, int i, int j) {
  anytype tmp = arr[i];
  arr[i] = arr[j];
  arr[j] = tmp;
 }
 
 public static <anytype extends comparable<? super anytype>> void mergesort(anytype[] arr) {
  anytype[] tmp = ((anytype[]) new comparable[arr.length]);
  mergesort(arr, 0, arr.length - 1, tmp);
 }
 
 private static <anytype extends comparable<? super anytype>> 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 <anytype extends comparable<? super anytype>> 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 <= mid) {
   tmp[k++] = arr[i++];
  }
 
  while (j <= end) {
   tmp[k++] = arr[j++];
  }
 
  for (int m = start; m <= end; m++) {
   arr[m] = tmp[m];
  }
 }
 
 public static <anytype extends comparable<? super anytype>> void quicksort(anytype[] arr) {
  quicksort(arr, 0, arr.length - 1);
 }
 
 private static <anytype extends comparable<? super anytype>> 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 extends comparable<? super anytype>> 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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