二分搜索

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internal static int InternalBinarySearch(
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  T[] array,
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  int index,
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  int length,
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  T value,
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  IComparer<T> comparer)
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{
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  int num1 = index;
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  int num2 = index + length - 1;
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  while (num1 <= num2)
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  {
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    int index1 = num1 + (num2 - num1 >> 1);
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    int num3 = comparer.Compare(array[index1], value);
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    if (num3 == 0)
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      return index1;
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    if (num3 < 0)
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      num1 = index1 + 1;
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    else
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      num2 = index1 - 1;
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  }
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  return ~num1;
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}