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### 题目描述

Given two version numbers, `version1` and `version2`, compare them.

Version numbers consist of one or more revisions joined by a dot `'.'`. Each revision consists of digits and may contain leading zeros. Every revision contains at least one character. Revisions are 0-indexed from left to right, with the leftmost revision being revision 0, the next revision being revision 1, and so on. For example `2.5.33` and `0.1` are valid version numbers.

To compare version numbers, compare their revisions in left-to-right order. Revisions are compared using their integer value ignoring any leading zeros. This means that revisions `1` and `001` are considered equal. If a version number does not specify a revision at an index, then treat the revision as `0`. For example, version `1.0` is less than version `1.1` because their revision 0s are the same, but their revision 1s are `0` and `1` respectively, and `0` < `1`.

Return the following:

• If `version1` < `version2`, return `-1`.
• If `version1` > `version2`, return `1`.
• Otherwise, return `0`.

### 例子

#### 例子 1

Input: version1 = “1.01”, version2 = “1.001”
Output: 0
Explanation: Ignoring leading zeroes, both “01” and “001” represent the same integer “1”.

#### 例子 2

Input: version1 = “1.0”, version2 = “1.0.0”
Output: 0
Explanation: version1 does not specify revision 2, which means it is treated as “0”.

#### 例子 3

Input: version1 = “0.1”, version2 = “1.1”
Output: -1
Explanation: version1’s revision 0 is “0”, while version2’s revision 0 is “1”. 0 < 1, so version1 < version2.

#### 例子 3

Input: version1 = “1.0.1”, version2 = “1”
Output: 1

#### 例子 3

Input: version1 = “7.5.2.4”, version2 = “7.5.3”
Output: -1

### Constraints

• `1 <= version1.length, version2.length <= 500`
• `version1` and `version2` only contain digits and `'.'`.
• `version1` and `version2` are valid version numbers.
• All the given revisions in `version1` and `version2` can be stored in a 32-bit integer.

### 解题思路

• 时间复杂度: O(n)
• 空间复杂度: O(1)

GitHub 代码同步地址： 165.CompareVersionNumbers.cpp

GitHub: Leetcode-C++-Solution