Basic Calculator II: Evaluate Expression with +, -, *, / Operators

bytedance Given a string s which represents a mathematical expression, evaluate the expression and return its value. The expression contains non-negative integers, +, -, *, and / operators as well as spaces. The operators have the usual precedence: * and / have higher precedence than + and -. Assume that the input is always a valid expression. Examples: Input: "3+2*2" Output: 7 Input: " 3/2 " Output: 1 Input: " 3+5 / 2 " Output: 5 Constraints: 1 <= s.length <= 10^5 s consists of integers and operators ('+', '-', '*', '/') separated by some number of spaces. Integers are valid and fit within the 32-bit signed integer range. Example Input 3+2*2