Lunski's Clutter

Write a function to find the longest common prefix string amongst an array of strings.

If there is no common prefix, return an empty string “”.

Example 1:

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Input: strs = ["flower","flow","flight"]
Output: "fl"

Example 2:

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Input: strs = ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.

Constraints:

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0 <= strs.length <= 200
0 <= strs[i].length <= 200
strs[i] consists of only lower-case English letters.

Given a 32-bit signed integer, reverse digits of an integer.

Note: Assume we are dealing with an environment that could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For this problem, assume that your function returns 0 when the reversed integer overflows.

Example 1:

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Input: x = 123
Output: 321

Example 2:

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Input: x = -123
Output: -321

Example 3:

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Input: x = 120
Output: 21

Example 4:

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Input: x = 0
Output: 0

Constraints:

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-2ˆ31 <= x <= 231 - 1

上次跟大家提到重訓的吃，接下來就是開始動，問題是怎麼動呢？ 其實我一開始也不知道，所以這份課表叫十里坡，在不斷努力後，還是練成了劍神。

Given an integer n, return true if it is a power of three. Otherwise, return false.

An integer n is a power of three, if there exists an integer x such that n == 3x.

Example 1:

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Input: n = 27
Output: true

Example 2:

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Input: n = 0
Output: false

Example 3:

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Input: n = 9
Output: true

Example 4:

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Input: n = 45
Output: false