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

Description

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

 

Solutions

Solution: String

• Time complexity: O(n)
• Space complexity: O(n)

 

JavaScript

/**
 * @param {string} s
 * @param {number} k
 * @return {boolean}
 */
const hasAllCodes = function (s, k) {
  const targetCount = 2 ** k;
  const codeSet = new Set();

  for (let index = k; index <= s.length; index++) {
    const code = s.slice(index - k, index);

    codeSet.add(code);
    if (codeSet.size === targetCount) return true;
  }
  return false;
};