Description
Given a binary array nums, return the maximum number of consecutive 1's in the array.
Example 1:
Input: nums = [1,1,0,1,1,1]
Output: 3
Explanation: The first two digits or the last three digits are consecutive 1s. The maximum number of consecutive 1s is 3.
Example 2:
Input: nums = [1,0,1,1,0,1]
Output: 2
Constraints:
1 <= nums.length <= 105nums[i] is either 0 or 1.
Solutions
Solution 1: Single Pass
We can iterate through the array, using a variable cnt to record the current number of consecutive 1s, and another variable ans to record the maximum number of consecutive 1s.
When we encounter a 1, we increment cnt by one, and then update ans to be the maximum of cnt and ans itself, i.e., ans = max(ans, cnt). Otherwise, we reset cnt to 0.
After the iteration ends, we return the value of ans.
The time complexity is O(n), where n is the length of the array. The space complexity is O(1).
PythonJavaC++GoTypeScriptRustJavaScriptPHP
class Solution:
def findMaxConsecutiveOnes(self, nums: List[int]) -> int:
ans = cnt = 0
for x in nums:
if x:
cnt += 1
ans = max(ans, cnt)
else:
cnt = 0
return ans(code-box)
class Solution {
public int findMaxConsecutiveOnes(int[] nums) {
int ans = 0, cnt = 0;
for (int x : nums) {
if (x == 1) {
ans = Math.max(ans, ++cnt);
} else {
cnt = 0;
}
}
return ans;
}
}(code-box)
class Solution {
public:
int findMaxConsecutiveOnes(vector<int>& nums) {
int ans = 0, cnt = 0;
for (int x : nums) {
if (x) {
ans = max(ans, ++cnt);
} else {
cnt = 0;
}
}
return ans;
}
};(code-box)
func findMaxConsecutiveOnes(nums []int) (ans int) {
cnt := 0
for _, x := range nums {
if x == 1 {
cnt++
ans = max(ans, cnt)
} else {
cnt = 0
}
}
return
}(code-box)
function findMaxConsecutiveOnes(nums: number[]): number {
let [ans, cnt] = [0, 0];
for (const x of nums) {
if (x) {
ans = Math.max(ans, ++cnt);
} else {
cnt = 0;
}
}
return ans;
}(code-box)
impl Solution {
pub fn find_max_consecutive_ones(nums: Vec<i32>) -> i32 {
let mut ans = 0;
let mut cnt = 0;
for &x in nums.iter() {
if x == 1 {
cnt += 1;
ans = ans.max(cnt);
} else {
cnt = 0;
}
}
ans
}
}(code-box)
/**
* @param {number[]} nums
* @return {number}
*/
var findMaxConsecutiveOnes = function (nums) {
let [ans, cnt] = [0, 0];
for (const x of nums) {
if (x) {
ans = Math.max(ans, ++cnt);
} else {
cnt = 0;
}
}
return ans;
};(code-box)
class Solution {
/**
* @param Integer[] $nums
* @return Integer
*/
function findMaxConsecutiveOnes($nums) {
$ans = $cnt = 0;
foreach ($nums as $x) {
if ($x == 1) {
$cnt += 1;
$ans = max($ans, $cnt);
} else {
$cnt = 0;
}
}
return $ans;
}
}(code-box)
