Calculator-227,224 - 8/25/2024

227:Given a string s which represents an expression, evaluate this expression and return its value. s consists of integers and operators (’+’, ’-’, ’*’, ’/’) separated by some number of spaces.

function calculate(s: string): number {
  function isNum(s: string) {
    return !isNaN(+s);
  }
  s;

  let c = "";
  let sign = "+";
  let num = 0;
  const stack = [];
  s = s.replace(/\s+/g, "");

  for (let i = 0; i < s.length; i++) {
    c = s[i];

    if (isNum(c)) {
      num = num * 10 + +c;
    }

    if (i === s.length - 1 || !isNum(c)) {
      switch (sign) {
        case "+":
          stack.push(num);
          break;
        case "-":
          stack.push(-num);
          break;
        case "*":
          stack[stack.length - 1] *= num;
          break;
        case "/":
          stack[stack.length - 1] = Math.trunc(stack[stack.length - 1] / num);
          break;
      }
      sign = c;
      num = 0;
    }
  }

  return stack.reduce((arr, cur) => arr + cur, 0);
}

224: s consists of digits, ’+’, ’-’,’*’,’/’, ’(’, ’)’, and ’ ‘.

function calculate(s: string): number {
  function isNum(s: string) {
    return !isNaN(+s);
  }

  function dfs(s: string, i: number): [number, number] {
    let c = "";
    let sign = "+";
    let num = 0;
    const stack = [];
    s = s.replace(/\s+/g, "");

    while (i < s.length) {
      c = s[i];

      if (isNum(c)) {
        num = num * 10 + +c;
      }

      if (c === "(") {
        const [res, newIndex] = dfs(s, i + 1);
        num = res;
        i = newIndex; // Move the index forward
      }

      if (i === s.length - 1 || (!isNum(c) && c !== "(" && c !== " ")) {
        switch (sign) {
          case "+":
            stack.push(num);
            break;
          case "-":
            stack.push(-num);
            break;
          case "*":
            stack[stack.length - 1] *= num;
            break;
          case "/":
            stack[stack.length - 1] = Math.trunc(stack[stack.length - 1] / num);
            break;
        }
        sign = c;
        num = 0;
      }

      if (c === ")") {
        break; // Break out of the loop if a closing parenthesis is encountered
      }

      i++;
    }
    return [stack.reduce((arr, cur) => arr + cur, 0), i];
  }

  return dfs(s, 0)[0];
}