3192. Minimum Operations to Make Binary Array Elements Equal to One II

Problem Link

Description

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You are given a binary array nums.

You can do the following operation on the array any number of times (possibly zero):

• Choose any index i from the array and flip all the elements from index i to the end of the array.

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.

 

Example 1:

Input: nums = [0,1,1,0,1]

Output: 4

Explanation:
We can do the following operations:

• Choose the index i = 1. The resulting array will be nums = [0,0,0,1,0].
• Choose the index i = 0. The resulting array will be nums = [1,1,1,0,1].
• Choose the index i = 4. The resulting array will be nums = [1,1,1,0,0].
• Choose the index i = 3. The resulting array will be nums = [1,1,1,1,1].

Example 2:

Input: nums = [1,0,0,0]

Output: 1

Explanation:
We can do the following operation:

• Choose the index i = 1. The resulting array will be nums = [1,1,1,1].

 

Constraints:

• 1 <= nums.length <= 105
• 0 <= nums[i] <= 1

Solution

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Python3

class Solution:
    def minOperations(self, nums: List[int]) -> int:
        N = len(nums)
        change = 0
        res = 0
        
        for x in nums:
            if change % 2 == x:
                change += 1
                res += 1
        
        return res