How do I generate a string with odd counts of characters?

To generate a string with odd counts, if n is odd, return a string with only 'a' repeated n times. If n is even, use n-1 'a's followed by a 'b'.

What is the optimal time complexity for this problem?

The optimal time complexity is O(n) because we are constructing a string of length n directly with minimal operations.

Can I use characters other than 'a' and 'b'?

While 'a' and 'b' are the simplest choice, any two distinct characters can be used to form the required odd counts.

How can I handle small values of n, like n = 1?

When n = 1, simply return 'a' as it satisfies the condition of an odd count of a single character.

What should I do if n is very large, such as 500?

For large n, the same solution applies. Construct the string directly with 'a' repeated n times if n is odd, or n-1 'a's and 1 'b' if n is even.

#1374

Easy

auto_awesomeString-driven solution strategy

LeetCode 题解工作台

生成每种字符都是奇数个的字符串

给你一个整数 n ，请你返回一个含 n 个字符的字符串，其中每种字符在该字符串中都恰好出现奇数次。返回的字符串必须只含小写英文字母。如果存在多个满足题目要求的字符串，则返回其中任意一个即可。示例 1：输入： n = 4 输出： "pppz" 解释： "pppz" 是一个满足题目要求的字符串…

字符串

题目描述

给你一个整数 n，请你返回一个含 n 个字符的字符串，其中每种字符在该字符串中都恰好出现 奇数次 。

返回的字符串必须只含小写英文字母。如果存在多个满足题目要求的字符串，则返回其中任意一个即可。

示例 1：

输入：n = 4
输出："pppz"
解释："pppz" 是一个满足题目要求的字符串，因为 'p' 出现 3 次，且 'z' 出现 1 次。当然，还有很多其他字符串也满足题目要求，比如："ohhh" 和 "love"。

示例 2：

输入：n = 2
输出："xy"
解释："xy" 是一个满足题目要求的字符串，因为 'x' 和 'y' 各出现 1 次。当然，还有很多其他字符串也满足题目要求，比如："ag" 和 "ur"。

示例 3：

输入：n = 7
输出："holasss"

提示：

1 <= n <= 500

lightbulb

解题思路

方法一：构造

如果 $n$ 为奇数，那么直接构造 $n$ 个 'a' 即可。

如果 $n$ 为偶数，那么构造 $n-1$ 个 'a' 和 $1$ 个 'b' 即可。

时间复杂度 $O(n)$ ，空间复杂度 $O(n)$ 。其中 $n$ 为字符串长度。

1

2

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class Solution:
    def generateTheString(self, n: int) -> str:
        return 'a' * n if n & 1 else 'a' * (n - 1) + 'b'

speed

复杂度分析

指标	值
时间	Depends on the final approach
空间	Depends on the final approach

psychology

面试官常问的追问

外企场景

question_mark
Candidate demonstrates understanding of string manipulation patterns.
question_mark
Candidate recognizes that the problem requires efficient handling of odd counts in string construction.
question_mark
Candidate can adapt the solution for various input sizes, particularly edge cases.

warning

常见陷阱

外企场景

error
Failing to account for n = 1 and constructing the string incorrectly for small values.
error
Confusing the need for odd counts with simply returning any random string of length n.
error
Not recognizing the efficiency of directly constructing the string with specific characters ('a' and 'b').

swap_horiz

进阶变体

外企场景

arrow_right_alt
Modify the problem to use uppercase letters instead of lowercase.
arrow_right_alt
Change the problem to require multiple different characters with odd counts.
arrow_right_alt
Allow characters other than 'a' and 'b' to be used to satisfy the condition.

help

常见问题

外企场景

继续练习

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