# Minimum length subarray of 1s in a Binary Array

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

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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++ 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 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. `

 `# 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# 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.. `

Output:
```2
```

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

Striver(underscore)79 at Codechef and codeforces D

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Improved By : jit_t, Rajput-Ji

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