图灵学院JAVA高级架构师【第四期】

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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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