Freaks City

To solve this problem, we scan every possible 2x2 submatrix in a n × m grid and check whether the four characters within it collectively contain at least one 'y', one 'o', and one 'u'. The order does not matter—only the presence of all three required characters. The algorithm iterates over all valid top-left corners of 2x2 blocks (from row 1 to ...

Problem Analysis Given an integer n, a binary string sequence is defined where: S1 = "0" Si = Si-1 + "1" + reverse(invert(Si-1)) for i > 1 The task is to find the k-th character in Sn. Key Observations Examining the pattern reveals a recursive structure: S1 has length 1 S2 has length 3 S3 has length 7 In general, |Sn| ...

Spinning Around Given a binary string (S) of length (n) with exactly one 1. In each operation, you can reverse a substring of length (k). For each position (i), find the minimum number of operations to move the 1 to position (i). Some positions are forbidden and cannot hold the 1 during the process. If no such number exists, output (-1). (n \le ...