Modified Basic Calculator

Basic Calculator Medium · Topics · Company Tags · Hints

Implement a calculator that evaluates a string containing a mathematical expression. The expression consists of non-negative integers and the operators +, -, *, /, as well as parentheses ( and ). The entire string represents a valid expression, and division between two integers should truncate toward zero (i.e., round down for positive results, effectively dropping the fractional part).

Input Format: A single line containing the expression string.

Output Format: The integer result of evaluating the expression.

Example 1:

Input: "3 + 2 * 2"

Output: 7

Explanation: Multiplication has higher precedence, so we compute 2 * 2 = 4 first, then add 3 to get 7.

Example 2:

Input: "10 / 3 + 1"

Output: 4

Explanation: 10 / 3 truncates to 3, plus 1 yields 4.

Example 3:

Input: "(8 - 3) * (4 + 6) / 2"

Output: 25

Explanation: 8 - 3 = 5, 4 + 6 = 10, multiply to get 50, then divide by 2 for a final result of 25.

Constraints:

• 1 <= expression.length <= 10,000
• The expression contains only digits 0-9, the operators +, -, *, /, parentheses ( and ), and optional spaces.
• All integers in the expression are non-negative.
• The input is guaranteed to be a syntactically valid arithmetic expression.
• Intermediate values and the final result fit within a 32-bit signed integer.