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# Check if every pair of 1 in the array is at least K length apart from each other

• Last Updated : 27 Sep, 2022

Given a binary array and an integer K, check if every pair of 1 in the array is at least K length apart from each other. Return true if the condition holds, otherwise return false.

Examples:

Input: arr = [1, 0, 0, 0, 1, 0, 0, 1, 0, 0], K = 2.
Output: True
Explanation:
Every 1 in the array is at least K distance apart from each other.

Input: arr= [1, 0, 1, 0, 1, 1], K = 1
Output: False
Explanation:
The fifth 1 and sixth 1 are not apart from each other. Hence, the output is false.

Approach:
To solve the problem mentioned above we have to check the distance between each pair of adjacent 1. Find the first position of 1 then iterate through the rest of the array and increment distance if it’s 0 otherwise perform a check operation if the distance is less than k and reset the count to 0 again.
Below is the implementation of the above approach:

## C++

 `// C++ implementation to Check if every pair of 1 in` `// the array is at least K length from each other`   `#include ` `using` `namespace` `std;`   `// Function to check distance` `bool` `kLengthApart(vector<``int``>& nums, ``int` `k)` `{` `    ``// Find first position of 1` `    ``int` `pos = 0, count = 0;`   `    ``while` `(pos < nums.size() && nums[pos] == 0)` `        ``pos++;`   `    ``// Iterate through the rest of array` `    ``for` `(``int` `i = pos + 1; i < nums.size(); i++) {` `        ``// Increment distance if its 0` `        ``if` `(nums[i] == 0)` `            ``count++;`   `        ``// Check if the distance is less than k` `        ``else` `{` `            ``if` `(count < k)` `                ``return` `false``;`   `            ``// Reset count to 0` `            ``count = 0;` `        ``}` `    ``}`   `    ``// Return the result` `    ``return` `true``;` `}`   `// Driver code` `int` `main()` `{` `    ``vector<``int``> nums = { 1, 0, 0, 0, 1, 0, 0, 1, 0, 0 };` `    ``int` `k = 2;`   `    ``bool` `ans = kLengthApart(nums, k);` `    ``if` `(ans == 1)` `        ``cout << ``"True"` `<< endl;`   `    ``else` `        ``cout << ``"False"` `<< endl;`   `    ``return` `0;` `}`

## Java

 `// Java implementation to check if ` `// every pair of 1 in the array is ` `// at least K length from each other ` `class` `Main{` `    `  `// Function to check distance ` `public` `static` `boolean` `kLengthApart(``int``[] nums,` `                                   ``int` `k) ` `{ ` `    `  `    ``// Find first position of 1 ` `    ``int` `pos = ``0``, count = ``0``; `   `    ``while` `(pos < nums.length && nums[pos] == ``0``) ` `        ``pos++; `   `    ``// Iterate through the rest of array ` `    ``for``(``int` `i = pos + ``1``; i < nums.length; i++)` `    ``{` `        `  `       ``// Increment distance if its 0 ` `       ``if` `(nums[i] == ``0``) ` `           ``count++; ` `           `  `       ``// Check if the distance is less than k ` `       ``else` `       ``{ ` `           ``if` `(count < k) ` `               ``return` `false``; ` `               `  `           ``// Reset count to 0 ` `           ``count = ``0``; ` `       ``} ` `    ``} ` `    `  `    ``// Return the result ` `    ``return` `true``; ` `} `   `// Driver Code` `public` `static` `void` `main(String[] args)` `{` `    ``int``[] nums = { ``1``, ``0``, ``0``, ``0``, ``1``, ` `                   ``0``, ``0``, ``1``, ``0``, ``0` `}; ` `    ``int` `k = ``2``; ` `    ``boolean` `ans = kLengthApart(nums, k); ` `    `  `    ``if` `(ans) ` `        ``System.out.println(``"True"``);`   `    ``else` `        ``System.out.println(``"False"``);` `}` `}`   `// This code is contributed by divyeshrabadiya07`

## Python3

 `# Python3 implementation to check if ` `# every pair of 1 in the array is ` `# at least K length from each other `   `# Function to check distance` `def` `kLengthApart(nums, k):` `    `  `    ``# Find first position of 1 ` `    ``pos ``=` `0` `    ``count ``=` `0` `    `  `    ``while` `(pos < ``len``(nums) ``and` `nums[pos] ``=``=` `0``):` `        ``pos ``+``=` `1` `        `  `    ``# Iterate through the rest of list` `    ``for` `i ``in` `range``(pos ``+` `1``, ``len``(nums)):` `        `  `        ``# Increment distance if its 0 ` `        ``if` `nums[i] ``=``=` `0``:` `            ``count ``+``=` `1` `            `  `        ``# Check if the distance is less than k ` `        ``else` `:` `            ``if` `count < k:` `                ``return` `False` `                `  `            ``# Reset count to 0 ` `            ``count ``=` `0` `            `  `        ``# Return the result ` `    ``return` `True` `    `  `# Driver Code` `if` `__name__ ``=``=` `"__main__"``:` `     `  `    ``nums ``=` `[ ``1``, ``0``, ``0``, ``0``, ``1``, ``0``, ``0``, ``1``, ``0``, ``0` `]` `    ``k ``=` `2` `    `  `    ``print``(kLengthApart(nums, k))`   `# This code is contributed by rutvik_56`

## C#

 `// C# implementation to check if ` `// every pair of 1 in the array is ` `// at least K length from each other ` `using` `System;`   `class` `GFG{` `    `  `// Function to check distance ` `public` `static` `bool` `kLengthApart(``int``[] nums,` `                                ``int` `k) ` `{ ` `    `  `    ``// Find first position of 1 ` `    ``int` `pos = 0, count = 0; `   `    ``while` `(pos < nums.Length && nums[pos] == 0) ` `        ``pos++; `   `    ``// Iterate through the rest of array ` `    ``for``(``int` `i = pos + 1; i < nums.Length; i++)` `    ``{` `       `  `       ``// Increment distance if its 0 ` `       ``if` `(nums[i] == 0) ` `           ``count++; ` `           `  `       ``// Check if the distance is ` `       ``// less than k ` `       ``else` `       ``{ ` `           ``if` `(count < k) ` `               ``return` `false``; ` `           `  `           ``// Reset count to 0 ` `           ``count = 0; ` `       ``} ` `    ``} ` `    `  `    ``// Return the result ` `    ``return` `true``; ` `} `   `// Driver Code` `public` `static` `void` `Main()` `{` `    ``int``[] nums = { 1, 0, 0, 0, 1, ` `                   ``0, 0, 1, 0, 0 }; ` `    ``int` `k = 2; ` `    ``bool` `ans = kLengthApart(nums, k); ` `    `  `    ``if` `(ans) ` `        ``Console.Write(``"True"``);` `    ``else` `        ``Console.Write(``"False"``);` `}` `}`   `// This code is contributed by chitranayal`

## Javascript

 ``

Output:

`True`

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

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