# 1461. Check If a String Contains All Binary Codes of Size K

#### Medium

Given a binary string `s` and an integer `k`, return `true` *if every binary code of length* `k` *is a substring of* `s`. Otherwise, return `false`.

 

**Example 1:**

```
Input: s = "00110110", k = 2
Output: true
Explanation: The binary codes of length 2 are "00", "01", "10" and "11". They can be all found as substrings at indices 0, 1, 3 and 2 respectively.
```

**Example 2:**

```
Input: s = "0110", k = 1
Output: true
Explanation: The binary codes of length 1 are "0" and "1", it is clear that both exist as a substring. 
```

**Example 3:**

```
Input: s = "0110", k = 2
Output: false
Explanation: The binary code "00" is of length 2 and does not exist in the array.
```

 

**Constraints:**

* `1 <= s.length <= 5 * 105`
* `s[i]` is either `'0'` or `'1'`.
* `1 <= k <= 20`

```python
class Solution:
    def hasAllCodes(self, s: str, k: int) -> bool:
        # Total Possible Binary from k
        count = 1 << k
        # We will interate through given binary string s and will note down different binary substrings of length
        # k once we finish iterating if the set() contains equal possible substrings i.e 2^k then True otherwise
        # False
        group = set()
        for index in range(len(s)-k, -1, -1):
            group.add(s[index:index+k])
        return len(group) == count
    
```