Maximum Consecutive Ones

Given a binary array nums, return the maximum number of consecutive 1s in the array.

A binary array is an array that contains only 0s and 1s.

Optimal Solution#

Walk through the binary array with a single pass, maintaining a counter curr that increments on each 1 and resets to zero on each 0. Whenever we reset, we compare curr against the global maximum before clearing it. A final comparison after the loop handles the case where the array ends with a run of ones. This requires only two variables and runs in O(n) time with O(1) space — optimal since we must read every element at least once.

class Solution {
public:
    int findMaxConsecutiveOnes(vector<int>& nums) {
        int maxi = 0;

        int curr =0;
        for(int i=0;i<nums.size();i++){
            if(nums[i] != 1){
                maxi = max(maxi, curr);
                curr=0;
            }else{
                curr++;
            }
        }
        if(curr)
            maxi = max(maxi, curr);

        return maxi;
    }
};

Time Complexity: O(n)

Space Complexity: O(1)