/**

• 数组二分查找

• 必须是有序数组，找到返回索引，否则返回-1
  */
  public class ArrIndex {
  public static void main(String[] args) {
  int[] arr = new int[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
  int number = 5;
  int index = getArrIndex(arr, number);
  System.out.println(index);
  }

  private static int getArrIndex(int[] arr, int number) {
  int min = 0;
  int max = arr.length - 1;
  while (min <= max) {
  int mid = (min + max) >> 1;
  if (arr[mid] > number) {
  max = mid - 1;
  } else if (arr[mid] < number) {
  min = mid + 1;
  } else if (arr[mid] == number) {
  return mid;
  }
  }
  return -1;
  }
  }