#241 - Different Ways to Add Parentheses

Medium • View on LeetCode • View on GitHub

Problem Description

Given a string expression of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. You may return the answer in any order.

The test cases are generated such that the output values fit in a 32-bit integer and the number of different results does not exceed 104.

Solution

/**
 * @param {string} expression
 * @return {number[]}
 */
var diffWaysToCompute = function(expression) {
  const results = [];

  for (let i = 0; i < expression.length; i++) {
    if ('+-*'.includes(expression[i])) {
      const left = diffWaysToCompute(expression.slice(0, i));
      const right = diffWaysToCompute(expression.slice(i + 1));
      left.forEach(l => right.forEach(r =>
        results.push(expression[i] === '+' ? l + r : expression[i] === '-' ? l - r : l * r)));
    }
  }

  return results.length ? results : [+expression];
};