# Check if all elements of binary array can be made 1

Given a binary array Arr and an integer K. If the value at index i is 1 you can change 0 to 1 with in the range of ( i – K ) to ( i + K ).

The task is to determine whether all the elements of the array can be made 1 or not.

Examples:

Input: Arr = { 0, 1, 0, 1 }, K = 2
Output: 2

Input: Arr = { 1, 0, 0, 0, 0, 0, 1 }, K = 2
Output: 0

It is not possible to make all the elements equal to 1

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

Approach:
Here another array is being used to mark as 1 if we can reach that index.
For every index in the range of 1 to N if the value of Arr[i] is 1 then make a loop from (i – K) to (i + K) and update b[i] to 1.

At last check the entry of b[i], and it should be 1 for every i, if it is then print 1 else print 0.

Below is the implementation of the above approach:

## C++

 `// C++ implementation ` `#include ` `using` `namespace` `std; ` ` `  `// Function to print 1 if the ` `// it is possible to make all array ` `// element equal to 1 else 0 ` `void` `checkAllOnes(``int` `arr[], ``int` `n, ` `                 ``int` `k) ` `{ ` ` `  `    ``int` `brr[n]; ` ` `  `    ``// Iterating over the array ` `    ``for` `(``int` `i = 0; i < n; i++) { ` ` `  `        ``// If element is 1 ` `        ``if` `(arr[i] == 1) { ` ` `  `            ``int` `h = k + 1; ` `            ``int` `j = i; ` ` `  `            ``// Put b[j...j-k] = 0 ` `            ``while` `(j >= 0 && (h--)) { ` `                ``brr[j] = 1; ` `                ``j--; ` `            ``} ` ` `  `            ``h = k + 1; ` `            ``j = i; ` ` `  `            ``// Put b[j...j+k] = 0 ` `            ``while` `(j < n && (h--)) { ` `                ``brr[j] = 1; ` `                ``j++; ` `            ``} ` `        ``} ` `    ``} ` ` `  `    ``int` `flag = 0; ` ` `  `    ``// If any value in aux ` `    ``// array equal to 0 ` `    ``// then set flag ` `    ``for` `(``int` `i = 0; i < n; i++) { ` `        ``if` `(brr[i] == 0) { ` `            ``flag = 1; ` `            ``break``; ` `        ``} ` `    ``} ` ` `  `    ``// If flag is set this ` `    ``// means array after ` `    ``// conversion contains ` `    ``// 0 so print 0 ` `    ``if` `(flag == 1) ` `        ``cout << ``"0"``; ` ` `  `    ``// else print 1 ` `    ``else` `        ``cout << ``"1\n"``; ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` ` `  `    ``int` `arr[] = { 1, 0, 1, 0 }; ` `    ``int` `k = 2; ` `    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr); ` ` `  `    ``checkAllOnes(arr, n, k); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java implementation of above approach ` `class` `GFG  ` `{ ` `         `  `// Function to print 1 if the  ` `// it is possible to make all array  ` `// element equal to 1 else 0  ` `static` `void` `checkAllOnes(``int` `arr[],  ` `                         ``int` `n, ``int` `k)  ` `{  ` `    ``int` `brr[] = ``new` `int``[n];  ` ` `  `    ``// Iterating over the array  ` `    ``for` `(``int` `i = ``0``; i < n; i++)  ` `    ``{  ` ` `  `        ``// If element is 1  ` `        ``if` `(arr[i] == ``1``)  ` `        ``{  ` `            ``int` `h = k + ``1``;  ` `            ``int` `j = i;  ` ` `  `            ``// Put b[j...j-k] = 0  ` `            ``while` `((j >= ``0``) && (h-- != ``0``)) ` `            ``{  ` `                ``brr[j] = ``1``;  ` `                ``j--;  ` `            ``}  ` ` `  `            ``h = k + ``1``;  ` `            ``j = i;  ` ` `  `            ``// Put b[j...j+k] = 0  ` `            ``while` `((j < n) && (h-- != ``0``))  ` `            ``{  ` `                ``brr[j] = ``1``;  ` `                ``j++;  ` `            ``}  ` `        ``}  ` `    ``}  ` ` `  `    ``int` `flag = ``0``;  ` ` `  `    ``// If any value in aux  ` `    ``// array equal to 0  ` `    ``// then set flag  ` `    ``for` `(``int` `i = ``0``; i < n; i++)  ` `    ``{  ` `        ``if` `(brr[i] == ``0``)  ` `        ``{  ` `            ``flag = ``1``;  ` `            ``break``;  ` `        ``}  ` `    ``}  ` ` `  `    ``// If flag is set this  ` `    ``// means array after  ` `    ``// conversion contains  ` `    ``// 0 so print 0  ` `    ``if` `(flag == ``1``)  ` `        ``System.out.println(``"0"``);  ` ` `  `    ``// else print 1  ` `    ``else` `        ``System.out.println(``"1"``);  ` `}  ` ` `  `// Driver Code  ` `public` `static` `void` `main (String[] args)  ` `{  ` `    ``int` `arr[] = { ``1``, ``0``, ``1``, ``0` `};  ` `    ``int` `k = ``2``;  ` `    ``int` `n = arr.length;  ` ` `  `    ``checkAllOnes(arr, n, k);  ` `}  ` `} ` ` `  `// This code is contributed by AnkitRai01 `

## Python3

 `# Python3 implementation ` ` `  `# Function to print 1 if the ` `# it is possible to make all array ` `# element equal to 1 else 0 ` `def` `checkAllOnes(arr, n, k): ` ` `  `    ``brr ``=` `[``0` `for` `i ``in` `range``(n)] ` ` `  `    ``# Iterating over the array ` `    ``for` `i ``in` `range``(n): ` ` `  `        ``# If element is 1 ` `        ``if` `(arr[i] ``=``=` `1``): ` ` `  `            ``h ``=` `k ``+` `1` `            ``j ``=` `i ` ` `  `            ``# Put b[j...j-k] = 0 ` `            ``while` `(j >``=` `0` `and` `(h)): ` `                ``brr[j] ``=` `1` `                ``h ``-``=` `1` `                ``j ``-``=` `1` ` `  `            ``h ``=` `k ``+` `1` `            ``j ``=` `i ` ` `  `            ``# Put b[j...j+k] = 0 ` `            ``while` `(j < n ``and` `(h)): ` `                ``brr[j] ``=` `1` `                ``j ``+``=` `1` `                ``h ``-``=` `1` ` `  `    ``flag ``=` `0` ` `  `    ``# If any value in aux ` `    ``# array equal to 0 ` `    ``# then set flag ` `    ``for` `i ``in` `range``(n): ` `        ``if` `(brr[i] ``=``=` `0``): ` `            ``flag ``=` `1` `            ``break` ` `  `    ``# If flag is set this ` `    ``# means array after ` `    ``# conversion contains ` `    ``# 0 so pr0 ` `    ``if` `(flag ``=``=` `1``): ` `        ``print``(``"0"``) ` ` `  `    ``# else pr1 ` `    ``else``: ` `        ``print``(``"1"``) ` ` `  `# Driver Code ` `arr ``=` `[``1``, ``0``, ``1``, ``0``] ` `k ``=` `2` `n ``=` `len``(arr) ` ` `  `checkAllOnes(arr, n, k) ` ` `  `# This code is contributed by Mohit Kumar `

## C#

 `// C# implementation of above approach ` `using` `System; ` `                     `  `class` `GFG  ` `{ ` `         `  `// Function to print 1 if the  ` `// it is possible to make all array  ` `// element equal to 1 else 0  ` `static` `void` `checkAllOnes(``int` `[]arr,  ` `                         ``int` `n, ``int` `k)  ` `{  ` `    ``int` `[]brr = ``new` `int``[n];  ` ` `  `    ``// Iterating over the array  ` `    ``for` `(``int` `i = 0; i < n; i++)  ` `    ``{  ` ` `  `        ``// If element is 1  ` `        ``if` `(arr[i] == 1)  ` `        ``{  ` `            ``int` `h = k + 1;  ` `            ``int` `j = i;  ` ` `  `            ``// Put b[j...j-k] = 0  ` `            ``while` `((j >= 0) && (h-- != 0)) ` `            ``{  ` `                ``brr[j] = 1;  ` `                ``j--;  ` `            ``}  ` ` `  `            ``h = k + 1;  ` `            ``j = i;  ` ` `  `            ``// Put b[j...j+k] = 0  ` `            ``while` `((j < n) && (h-- != 0))  ` `            ``{  ` `                ``brr[j] = 1;  ` `                ``j++;  ` `            ``}  ` `        ``}  ` `    ``}  ` ` `  `    ``int` `flag = 0;  ` ` `  `    ``// If any value in aux  ` `    ``// array equal to 0  ` `    ``// then set flag  ` `    ``for` `(``int` `i = 0; i < n; i++)  ` `    ``{  ` `        ``if` `(brr[i] == 0)  ` `        ``{  ` `            ``flag = 1;  ` `            ``break``;  ` `        ``}  ` `    ``}  ` ` `  `    ``// If flag is set this  ` `    ``// means array after  ` `    ``// conversion contains  ` `    ``// 0 so print 0  ` `    ``if` `(flag == 1)  ` `        ``Console.WriteLine(``"0"``);  ` ` `  `    ``// else print 1  ` `    ``else` `        ``Console.WriteLine(``"1"``);  ` `}  ` ` `  `// Driver Code  ` `public` `static` `void` `Main (String[] args)  ` `{  ` `    ``int` `[]arr = { 1, 0, 1, 0 };  ` `    ``int` `k = 2;  ` `    ``int` `n = arr.Length;  ` ` `  `    ``checkAllOnes(arr, n, k);  ` `}  ` `} ` ` `  `// This code is contributed by 29AjayKumar `

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