【每日一题Day92】LC2299强密码检验器 II | 模拟 状态压缩

强密码检验器 II【LC2299】

A password is said to be strong if it satisfies all the following criteria:

• It has at least 8 characters.
• It contains at least one lowercase letter.
• It contains at least one uppercase letter.
• It contains at least one digit.
• It contains at least one special character. The special characters are the characters in the following string: "!@#$%^&*()-+".
• It does not contain 2 of the same character in adjacent positions (i.e., "aab" violates this condition, but "aba" does not).

Given a string password, return true if it is a strong password. Otherwise, return false.

• 思路：首先判断密码长度是否大于等于8，若是则判断该密码是否包含至少一个数字、小写字母、大写字母以及特殊字符，并相邻字符不相同，若满足条件则返回true。

• 实现：使用一个变量记录该密码是否包含数字、小写字母、大写字母以及特殊字符，若都包含则返回true。

  class Solution {
      public boolean strongPasswordCheckerII(String password) {
          int n = password.length();
          if (n < 8){
              return false;
          }
          int flag = 0;
          for (int i = 0; i < password.length(); i++){
              char c = password.charAt(i);
              if (i > 0 && password.charAt(i - 1) == c){
                  return false;
              }
              if ( c >= '0' && c <= '9'){
                  flag |= 1 << 0;
              }else if ( c >= 'a' && c <= 'z'){
                  flag |= 1 << 1;
              }else if ( c >= 'A' && c <= 'Z'){
                  flag |= 1 << 2;
              }else{
                  flag |= 1 << 3;
              }
          }
          return flag >= 15;
      }
      
  }
  

  • 复杂度分析

    • 时间复杂度：$O(n)$
    • 空间复杂度：$O(1)$