二分搜索的三种模板

def binarySearch(nums, target):
    left, right = 0, len(nums) -1
    while left <= right:
        mid = (left + (right - left)) // 2
        if nums[mid] > target:
            right = mid - 1
        elif nums[mid] < target:
            left = mid + 1
        else:
            return mid
    # 没有就返回-1
    return -1

def binarySearch(nums, target):
    left, right = 0, len(nums) -1
    while left <= right:
        mid = left + (right - left) // 2
        if nums[mid] >= target:
            right = mid - 1
        elif nums[mid] < target:
            left = mid + 1
    if left < len(nums) and nums[left] == target:
      return left
    # 没有就返回-1
    return -1

  while left <= right:
        mid = left + (right - left) // 2
        if nums[mid] > target:
            right = mid - 1
        elif nums[mid] <= target:
            left = mid + 1
    if right >= 0 and nums[right] == target:
      return right
    # 没有就返回-1
    return -1

 while left <= right:
   mid = left + (right - left )// 2
   if nums[mid] > target:
    right = mid - 1
   elif nums[mid] <= target:
    left = mid + 1
 if left < n:
  return left
 else:
  return -1

结尾判断改为
 while left <= right:
   mid = left + (right - left )// 2
   if nums[mid] >= target:
    right = mid - 1
   elif nums[mid] < target:
    left = mid + 1
 if right >= 0:
  return right
 else:
  return -1