Max Consecutive Ones II

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Find max consecutive 1s if you can flip at most one 0.

Example 1
Input: nums=[1,0,1,1,0] → Output: 4
Example 2
Input: nums=[1,0,1,1,0,1] → Output: 4

Solution Approach

Sliding window tracking number of zeros flipped (at most 1).

  • Track left pointer and count of zeros in window
  • When zeros > 1: advance left, decrement zeros if left was 0
  • Track max window size
Java
public int findMaxConsecutiveOnes(int[] nums) {
    int left = 0, zeros = 0, max = 0;
    for (int right = 0; right < nums.length; right++) {
        if (nums[right] == 0) zeros++;
        while (zeros > 1) { if (nums[left++] == 0) zeros--; }
        max = Math.max(max, right - left + 1);
    }
    return max;
}
  • Time Complexity: O(n)
  • Space Complexity: O(1)