256. Max Consecutive Ones

Sweep once, growing a run of consecutive 1's and resetting it to 0 on every 0; track the largest run seen.

One pass

run = best = 0
for x in nums:
    if x == 1: run += 1; best = max(best, run)
    else: run = 0
return best

Worked example

[1,1,0,1,1,1] → runs 2 then 3 → 3.

Complexity

• Time: O(n).
• Space: O(1).

class Solution {
    public int findMaxConsecutiveOnes(int[] nums) {
        int best = 0, run = 0;
        for (int x : nums) {
            if (x == 1) {
                run++;
                best = Math.max(best, run);
            } else {
                run = 0;
            }
        }
        return best;
    }
}