78_minOperations.py

'''3191. Minimum Operations to Make Binary Array Elements Equal to One I
You are given a binary array nums.
You can do the following operation on the array any number of times (possibly zero):
Choose any 3 consecutive elements from the array and flip all of them.
Flipping an element means changing its value from 0 to 1, and from 1 to 0.
Return the minimum number of operations required to make all elements in nums equal to 1. If it is impossible, return -1.
Example 1:
Input: nums = [0,1,1,1,0,0]
Output: 3
Explanation:
We can do the following operations:
Choose the elements at indices 0, 1 and 2. The resulting array is nums = [1,0,0,1,0,0].
Choose the elements at indices 1, 2 and 3. The resulting array is nums = [1,1,1,0,0,0].
Choose the elements at indices 3, 4 and 5. The resulting array is nums = [1,1,1,1,1,1].'''
from typing import List
class Solution:
  def minOperations(self, nums: List[int]) -> int:
    ans=0
    for i in range(len(nums)-2):
      if nums[i]==0:
        nums[i]=not nums[i]
        nums[i+1]=not nums[i+1]
        nums[i+2]=not nums[i+2]
        ans+=1
    return ans if all(nums) else -1