Minimum Operations to Make Binary Array Elements Equal to One I

Leetcode Problem:

• Minimum Operations to Make Binary Array Elements Equal to One I

Summary

• Given a binary array, find the minimum number of operations to make all elements equal to 1 by flipping 3 consecutive elements at a time.

Approach

• The approach is to iterate through the array and flip 3 consecutive elements at a time until no more flips are possible
• If a 3 consecutive elements cannot be found, return -1.

Complexity

• O(n), where n is the number of elements in the array

Explanation

• The solution iterates through the array and checks if the current element and the next two elements are 0
• If they are, it flips them and increments the answer
• This process continues until no more flips are possible
• If at any point a 3 consecutive elements cannot be found, the function returns -1.

Solution Code:

class Solution {
public:
    int minOperations(vector& nums) {
        int ans = 0;
        for(int i = 0 ; i < nums.size(); i++){
            if(nums[i] == 0){
                for(int j = i; j < i + 3; j++){
                    if(j >= nums.size()) return -1;
                    nums[j] ^= 1;
                }
                ans++;
            }
        }
        return ans;
    }
};