CF1844D.Row Major

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.

一个 $r \times c$ 字符网格 $A$ 的行优先顺序（row-major order）是指将所有行依次连接所得到的字符串，即

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

若字符网格 $A$ 中存在两个相邻单元格（即共享一条边的单元格）具有相同的字符，则称该网格 $A$ 是坏的（bad）。

给定一个正整数 $n$。考虑所有仅由小写拉丁字母组成的字符串 $s$，且 $s$ 不是任何坏网格的行优先顺序。在所有长度为 $n$ 的此类字符串中，找出一个所含不同字符种类数最少的字符串。

可以证明：在本题约束条件下，至少存在一个满足要求的字符串。

Each test contains multiple test cases. The first line contains the number of test cases $t$ ($1 \le t \le 10^4$). The description of the test cases follows.

The only line of each test case contains a single integer $n$ ($1 \le n \le 10^6$).

It is guaranteed that the sum of $n$ over all test cases does not exceed $10^6$.

每个测试包含多个测试用例。第一行包含测试用例的数量 $t$（$1 \le t \le 10^4$）。随后是各测试用例的描述。

每个测试用例仅一行，包含一个整数 $n$（$1 \le n \le 10^6$）。

保证所有测试用例的 $n$ 值之和不超过 $10^6$。

For each test case, output a string with the minimum number of distinct characters among all suitable strings of length $n$.

If there are multiple solutions, print any of them.

对于每个测试用例，输出一个字符串，该字符串是所有长度为 $n$ 的合适字符串中不同字符数量最少的一个。

如果存在多个解，输出其中任意一个即可。

In the first test case, there are $3$ ways $s$ can be the row-major order of a grid, and they are all not bad:

t

t

h

t

h

a

t

h

a

t

a

t

It can be proven that $3$ distinct characters is the minimum possible.

In the second test case, there are $2$ ways $s$ can be the row-major order of a grid, and they are both not bad:

i

i

s

s

It can be proven that $2$ distinct characters is the minimum possible.

In the third test case, there is only $1$ way $s$ can be the row-major order of a grid, and it is not bad.

In the fourth test case, there are $4$ ways $s$ can be the row-major order of a grid, and they are all not bad:

t

t

o

t

o

m

t

o

m

a

t

o

o

m

a

a

t

o

m

t

o

a

t

o

It can be proven that $4$ distinct characters is the minimum possible. Note that, for example, the string "orange" is not an acceptable output because it has $6 \gt 4$ distinct characters, and the string "banana" is not an acceptable output because it is the row-major order of the following bad grid:

b

a

n

a

n

a

在第一个测试用例中，字符串 $s$ 作为某个网格的行优先顺序（row-major order）共有 $3$ 种可能的方式，且它们全都不构成“坏网格”：

t

t

h

t

h

a

t

h

a

t

a

t

可以证明，$3$ 个互不相同的字符是所能达到的最小值。

在第二个测试用例中，字符串 $s$ 作为某个网格的行优先顺序共有 $2$ 种可能的方式，且它们全都不构成“坏网格”：

i

i

s

s

可以证明，$2$ 个互不相同的字符是所能达到的最小值。

在第三个测试用例中，字符串 $s$ 作为某个网格的行优先顺序仅有 $1$ 种可能的方式，且该方式不构成“坏网格”。

在第四个测试用例中，字符串 $s$ 作为某个网格的行优先顺序共有 $4$ 种可能的方式，且它们全都不构成“坏网格”：

t

t

o

t

o

m

t

o

m

a

t

o

o

m

a

a

t

o

m

t

o

a

t

o

可以证明，$4$ 个互不相同的字符是所能达到的最小值。注意，例如字符串 "orange" 不是可接受的输出，因为它含有 $6 > 4$ 个互不相同的字符；而字符串 "banana" 也不是可接受的输出，因为它是如下“坏网格”的行优先顺序：

b

a

n

a

n

a