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

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Array Dynamic Programming Greedy

Time: O(n)

Space: O(1)

Intuition

Minimum operations to alternate binary array. Compare with patterns 010101... and 101010..., return min mismatches.

Algorithm

1Count mismatches with pattern starting with 0. Answer = min(mismatches, n - mismatches).

Common Pitfalls

•Two valid alternating patterns. Count mismatches with one, n-count for the other. Return min.

3192.cs

// Approach: Greedy; count flips needed tracking current parity.
// Time: O(n) Space: O(1)

public class Solution {
    public int MinOperations(int[] nums) {
        int n = nums.Length, ans = 0, times = 0;

        for(int i = 0; i < n; i++)
        {
            if((nums[i] == 1 && times % 2 == 1) || (nums[i] == 0 && times % 2 == 0))
                times++;
        }
        return times;
    }
}

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