Non-decreasing Array
改变序列中至多一个数,使之变成不增序列array[i] <= array[i + 1]
def nondecreasing(nums): one, two = nums[:], nums[:] for i in range(len(nums) - 1): if nums[i] > nums[i + 1]: one[i] = nums[i + 1] two[i + 1] = nums[i] break return one == sorted(one) or two == sorted(two)