Zusammenfassung der Java-Five-Sortieralgorithmus-Toolklasse

Diese Tool-Klasse fasst die fünf Sortieralgorithmen von Java einfach und klar zusammen: Schnellsortierung, Hill-Sortierung, Einfügesortierung, Heap-Sortierung und Zusammenführungssortierung. Im Code gibt es keine Erklärung Ich hoffe, Sie können die entsprechenden Anweisungen selbst überprüfen. Hier ist nur eine Zusammenfassung dieser Algorithmen für Ihre Verwendung.

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;
}