Basic Calculator II

Problem: Basic Calculator II Given a string s representing a valid arithmetic expression containing non-negative integers, spaces, and operators +, -, *, /, evaluate the expression and return the result. Rules & Constraints The expression may contain spaces. Operator precedence: * and / have higher precedence than + and -. Operators of the same precedence are evaluated left-to-right. Integer division truncates toward zero (e.g., 3/2 = 1, -3/2 = -1). The input expression is guaranteed to be valid. Input Format One line: string s Output Format Output one integer: the evaluated result. Constraints 1 <= len(s) <= 3e5 s consists of digits, spaces, and + - * / Intermediate results fit in 32-bit signed integer Examples Input: 3+2*2 -> Output: 7 Input: 3/2 -> Output: 1 Input: 3+5 / 2 -> Output: 5 Example Input 3+2*2 Output 7