# Minimum length subarray of 1s in a Binary Array

• Last Updated : 15 Mar, 2021

Given binary array. The task is to find the length of subarray with minimum number of 1s.
Note: It is guaranteed that there is atleast one 1 present in the array.
Examples

Input : arr[] = {1, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1}
Output : 3
Minimum length subarray of 1s is {1, 1}.
Input : arr[] = {0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1}
Output : 1

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Simple Solution: A simple solution is to consider every subarray and count 1’s in every subarray. Finally return return size of minimum length subarray of 1s.
Efficient Solution: An efficient solution is traverse array from left to right. If we see a 1, we increment count. If we see a 0, and count of 1s so far is positive, calculate minimum of count and result and reset count to zero.
Below is the implementation of the above approach:

## C++

 `// C++ program to count minimum length``// subarray of 1's in a binary array.``#include ``using` `namespace` `std;` `// Function to count minimum length subarray``// of 1's in binary array arr[0..n-1]``int` `getMinLength(``bool` `arr[], ``int` `n)``{``    ``int` `count = 0; ``// intitialize count``    ``int` `result = INT_MAX; ``// initialize result` `    ``for` `(``int` `i = 0; i < n; i++) {``        ``if` `(arr[i] == 1) {``            ``count++;``        ``}``        ``else` `{``            ``if` `(count != 0)``                ``result = min(result, count);``            ``count = 0;``        ``}``    ``}` `    ``return` `result;``}` `// Driver code``int` `main()``{``    ``bool` `arr[] = { 1, 1, 0, 0, 1, 1, 1, 0,``                   ``1, 1, 1, 1 };` `    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr);` `    ``cout << getMinLength(arr, n) << endl;` `    ``return` `0;``}`

## Java

 `// Java program to count minimum length``// subarray of 1's in a binary array.``import` `java.io.*;` `class` `GFG``{``    ` `// Function to count minimum length subarray``// of 1's in binary array arr[0..n-1]``static` `int` `getMinLength(``double` `arr[], ``int` `n)``{``    ``int` `count = ``0``; ``// intitialize count``    ``int` `result = Integer.MAX_VALUE; ``// initialize result` `    ``for` `(``int` `i = ``0``; i < n; i++)``    ``{``        ``if` `(arr[i] == ``1``)``        ``{``            ``count++;``        ``}``        ``else``        ``{``            ``if` `(count != ``0``)``                ``result = Math.min(result, count);``            ``count = ``0``;``        ``}``    ``}` `    ``return` `result;``}` `// Driver code``public` `static` `void` `main (String[] args)``{``    ``double` `arr[] = { ``1``, ``1``, ``0``, ``0``, ``1``, ``1``, ``1``, ``0``,``                ``1``, ``1``, ``1``, ``1` `};``    ``int` `n = arr.length;``    ``System.out.println (getMinLength(arr, n));` `}``}` `// This code is contributed by ajit.`

## Python3

 `# Python program to count minimum length``# subarray of 1's in a binary array.``import` `sys` `# Function to count minimum length subarray``# of 1's in binary array arr[0..n-1]``def` `getMinLength(arr, n):``    ``count ``=` `0``; ``# intitialize count``    ``result ``=` `sys.maxsize ; ``# initialize result` `    ``for` `i ``in` `range``(n):``        ``if` `(arr[i] ``=``=` `1``):``            ``count``+``=``1``;``        ``else``:``            ``if``(count !``=` `0``):``                ``result ``=` `min``(result, count);``            ``count ``=` `0``;` `    ``return` `result;` `# Driver code``arr ``=` `[ ``1``, ``1``, ``0``, ``0``, ``1``, ``1``, ``1``, ``0``,``                ``1``, ``1``, ``1``, ``1` `];` `n ``=` `len``(arr);` `print``(getMinLength(arr, n));` `# This code is contributed by Rajput-Ji`

## C#

 `// C# program to count minimum length``// subarray of 1's in a binary array.``using` `System;` `class` `GFG``{``    ` `// Function to count minimum length subarray``// of 1's in binary array arr[0..n-1]``static` `int` `getMinLength(``double` `[]arr, ``int` `n)``{``    ``int` `count = 0; ``// intitialize count``    ``int` `result = ``int``.MaxValue; ``// initialize result` `    ``for` `(``int` `i = 0; i < n; i++)``    ``{``        ``if` `(arr[i] == 1)``        ``{``            ``count++;``        ``}``        ``else``        ``{``            ``if` `(count != 0)``                ``result = Math.Min(result, count);``            ``count = 0;``        ``}``    ``}` `    ``return` `result;``}` `// Driver code``static` `public` `void` `Main ()``{``    ``double` `[]arr = { 1, 1, 0, 0, 1, 1,``                     ``1, 0, 1, 1, 1, 1 };``    ``int` `n = arr.Length;``    ``Console.WriteLine(getMinLength(arr, n));``}``}` `// This code is contributed by Tushil..`

## Javascript

 ``
Output:
`2`

Time Complexity: O(N)
Auxiliary Space: O(1)

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