1. Basic Calculator
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-negativeintegers and empty spaces.
You may assume that the given expression is always valid.
Some examples:
"1 + 1" = 2
" 2-1 + 2 " = 3
"(1+(4+5+2)-3)+(6+8)" = 23
2. Basic Calculator II
Implement a basic calculator to evaluate a simple expression string.
The expression string contains onlynon-negativeintegers,+,-,*,/operators and empty spaces. The integer division should truncate toward zero.
You may assume that the given expression is always valid.
Some examples:
"3+2*2" = 7
" 3/2 " = 1
" 3+5 / 2 " = 5