224. Basic Calculator | LeetCode | Top Interview 150 | Coding Questions

Problem Link https://leetcode.com/problems/basic-calculator/ Detailed Step-by-Step Explanation https://leetcode.com/problems/basic-calculator/solutions/7576826/most-optimal-beats-100-all-languages-sta-jd4n Solution class Solution { public int calculate(String s) { Stack<Integer> stack = new Stack<>(); int res = 0; int curr = 0; int sign = 1; for (char c : s.toCharArray()) { if (Character.isDigit(c)) { curr = curr * 10 + (c - '0'); } else if (c == '+') { res += curr * sign; sign = 1; curr = 0; } else if (c == '-') { res += curr * sign; sign = -1; curr = 0; } else if (c == '(') { stack.push(res); stack.push(sign); res = 0; sign = 1; curr = 0; } else if (c == ')') { res += curr * sign; curr = 0; res *= stack.pop(); res += stack.pop(); } } res += sign * curr; return res; } }