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Implement a basic calculator to evaluate a simple expression string.
The expression string may contain open ( and closing parentheses ),
the plus + or minus sign -, non-negative integers and empty
spaces .
Example 1:
Input: "1 + 1"
Output: 2
Example 2:
Input: " 2-1 + 2 "
Output: 3
Example 3:
Input: "(1+(4+5+2)-3)+(6+8)"
Output: 23
Note:
- You may assume that the given expression is always valid.
- Do not use the
eval built-in library function.
Difficulty:
Hard
Lock:
Normal
All contents and pictures on this website come from the Internet and are updated regularly every week. They are for personal study and research only, and should not be used for commercial purposes. Thank you for your cooperation.