rt， @小粉兔

题目描述

The row-major order of an $r \times c$ grid of characters $A$ is the string obtained by concatenating all the rows, i.e.

$A_{11}A_{12} \dots A_{1c}A_{21}A_{22} \dots A_{2c} \dots A_{r1}A_{r2} \dots A_{rc}.$

A grid of characters $A$ is bad if there are some two adjacent cells (cells sharing an edge) with the same character.

You are given a positive integer $n$ . Consider all strings $s$ consisting of only lowercase Latin letters such that they are not the row-major order of any bad grid. Find any string with the minimum number of distinct characters among all such strings of length $n$.

It can be proven that at least one such string exists under the constraints of the problem.