162. Find Peak Element

我在做 binary search 的时候，没有考虑 mid 有没有被访问到的情况。

class Solution(object):
    def findPeakElement(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        n = len(nums)
        if n == 0: return
        if n == 1: return 0
        if nums[0] > nums[1]: return 0
        if nums[-1] > nums[-2]: return n - 1

#         for i in range(1, n - 1):
#             if nums[i] > nums[i - 1] and nums[i] > nums[i + 1]: return i
        '''
        Since nums[-1] == nums[n] == -∞.
        '''

#         i = 1
#         j = n - 2
#         while i <= j:
#             if nums[i] > nums[i - 1] and nums[i] > nums[i + 1]: return i
#             if nums[j] > nums[j - 1] and nums[j] > nums[j + 1]: return j

#             mid = int((i + j) / 2)
#             # in this case, I ignore to compare mid, just jump to mid + 1
#             if nums[mid] > nums[mid - 1]: i = mid + 1
#             else:
#                 j = mid
        i = 1
        j = n - 2
        while i <= j:
            if nums[i] > nums[i - 1] and nums[i] > nums[i + 1]: return i
            if nums[j] > nums[j - 1] and nums[j] > nums[j + 1]: return j

            mid = int((i + j) / 2)
            if nums[mid] > nums[mid - 1] and nums[mid] > nums[mid + 1]: return mid
            if nums[mid] > nums[mid - 1]: i = mid + 1
            else:
                j = mid