最长乘积奇数的子阵列

给定一个由N个元素组成的数组arr [] ，任务是找到具有奇积的最长子数组的长度。

例子：

Input: arr[] = {3, 5, 2, 1} 
Output: 2 
Explanation: 
Subarrays with consecutive odd elements are {3, 5}, and {1}. 
Since, {3, 5} is the longer, the answer is 2.

Input: arr[] = {8, 5, 3, 1, 0} 
Output: 3 
Explanation: 
Longest subarray with odd product is {5, 3, 1}. 

方法：
要解决此问题，需要进行以下观察：

The Product of two odd numbers generates an odd number. 
The Product of one odd and one even number generates an even number. 
The Product of two even numbers generates an even number. 

从上面的观察，我们可以得出结论，数组中连续奇数元素的最长子数组是必需的答案。
请按照以下步骤解决问题：

• 遍历数组并检查当前元素是偶数还是奇数。
• 如果当前元素为奇数，则将count设置为1并保持递增计数，直到在数组中遇到偶数元素为止。
• 遇到偶数元素后，将count与ans进行比较，并更新ans存储两者的最大值。
• 对其余阵列重复上述步骤。
• 最后，打印存储在ans中的值。

下面是上述方法的实现：

C++

// C++ Program to find the longest
// subarray with odd product
#include 
using namespace std;
  
// Function to return length of
// longest subarray with odd product
int Maxlen(int arr[], int n)
{
    int ans = 0;
    int count = 0;
    for (int i = 0; i < n; i++) {
  
        // If even element
        // is encountered
        if (arr[i] % 2 == 0)
            count = 0;
        else
            count++;
  
        // Update maximum
        ans = max(ans, count);
    }
    return ans;
}
  
// Driver Code
int main()
{
  
    // int arr[] = { 6, 3, 5, 1 };
    int arr[] = { 1, 7, 2 };
    int n = sizeof(arr) / sizeof(int);
  
    cout << Maxlen(arr, n) << endl;
    return 0;
}

Java

// Java program to find the longest
// subarray with odd product
import java.util.*;
  
class GFG{
      
// Function to return length of
// longest subarray with odd product
static int Maxlen(int arr[], int n)
{
    int ans = 0;
    int count = 0;
    for(int i = 0; i < n; i++)
    {
          
        // If even element
        // is encountered
        if (arr[i] % 2 == 0)
            count = 0;
        else
            count++;
  
        // Update maximum
        ans = Math.max(ans, count);
    }
    return ans;
}
  
// Driver Code
public static void main(String s[])
{
    int arr[] = { 1, 7, 2 };
    int n = arr.length;
      
    System.out.println(Maxlen(arr, n));
} 
}
  
// This code is contributed by rutvik_56

Python3

# Python3 program to find the longest 
# subarray with odd product
  
# Function to return length of 
# longest subarray with odd product 
def Maxlen(a, n):
      
    ans = 0
    count = 0
      
    for i in range(n): 
  
        # If even element 
        # is encountered 
        if a[i] % 2 == 0: 
            count = 0
        else: 
            count += 1
              
        # Update maximum 
        ans = max(ans, count)
          
    return ans
  
# Driver code
arr = [ 1, 7, 2 ] 
n = len(arr) 
  
print(Maxlen(arr, n))
  
# This code is contributed by amreshkumar3

C#

// C# program to find the longest 
// subarray with odd product 
using System; 
  
class GFG{ 
  
// Function to return length of 
// longest subarray with odd product 
static int Maxlen(int []arr, int n) 
{ 
    int ans = 0; 
    int count = 0; 
      
    for(int i = 0; i < n; i++) 
    { 
          
        // If even element 
        // is encountered 
        if (arr[i] % 2 == 0) 
            count = 0; 
        else
            count++; 
      
        // Update maximum 
        ans = Math.Max(ans, count); 
    } 
    return ans; 
} 
  
// Driver Code 
public static void Main() 
{ 
    int []arr = { 1, 7, 2 }; 
    int n = arr.Length; 
      
    Console.WriteLine(Maxlen(arr, n)); 
} 
} 
  
// This code is contributed by amreshkumar3

输出：

2

时间复杂度： O(N)
辅助空间： O(1)