2022-05-31 Daily-Challenge

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Today I have done leetcode's May LeetCoding Challenge with cpp.

May LeetCoding Challenge 31

Description

Check If a String Contains All Binary Codes of Size K

​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

Solution

class Solution {
public:
  bool hasAllCodes(string s, int k) {
    int len = s.length();
    if((1 << k) > len - k + 1) return false;
    int cur = 0;
    const int MASK = (1 << k) - 1;
    vector<bool> has(1 << k);
    for(int i = 0; i < k; ++i) {
      cur <<= 1;
      cur |= (s[i] == '1');
    }
    has[cur] = true;
    for(int i = k; i < len; ++i) {
      cur <<= 1;
      cur |= (s[i] == '1');
      cur &= MASK;
      has[cur] = true;
    }
    for(auto b : has) if(!b) return false;
    return true;
  }
};

// Accepted
// 200/200 cases passed (92 ms)
// Your runtime beats 88.99 % of cpp submissions
// Your memory usage beats 99.37 % of cpp submissions (17.4 MB)
Algorithm