Bug in challenge: Rosetta Code: 24 Game

Describe your problem and how to reproduce it: My solution (see below) produces the correct result: For solve24("4878") my algorithm produces (4-8+7)*(8) which equals 24. However the automated test on this example fails - error message: solve24("4878") should return (7-8/8)*4 or 4*(7-8/8).

My Code:

function solve24 (numStr) {

  // Generate all possible combinations of ordering the numbers
  let numberCombinations = [];

  for (let i1=0; i1<4; i1++) {
    for (let i2=0; i2<4; i2++) {
      for (let i3=0; i3<4; i3++) {
        // not very elegant but short and simple ...
        if (i1 !== i2 && i2 !== i3 && i1 !== i3) {
          let i4 = 6 - i1 - i2 - i3;
          numberCombinations.push([
            numStr[i1], numStr[i2], numStr[i3], numStr[i4]
          ])
        }
      }
    }
  }

  // Format: "_n_n_n_n_"

  // Choices for symbols to fill in the gaps
  const startChoices = ["", "(", "(("];
  const midChoices = ["+", "-", "*", "/", 
  "(", ")", "((", "))", ")*(", ")/("];
  const endChoices = ["", ")", "))"];
  
  // Iterate through all number combinations
  for (let i=0; i<24; i++) {

    let combination = numberCombinations[i];

    // Again ... not pretty but simple and stupid
    for (let i1=0; i1<3; i1++) {
      for (let i5=0; i5<3; i5++) {

        for (let i2=0; i2<10; i2++) {
          for (let i3=0; i3<10; i3++) {
            for (let i4=0; i4<10; i4++) {
      
                let mathString = 
                startChoices[i1] + combination[0] + midChoices[i2] +
                combination[1] + midChoices[i3] + combination[2] +
                midChoices[i4] +combination[3] +endChoices[i5];

                try {
                  if (eval(mathString) == 24) {
                    return(mathString);
                  }
                } catch (e) {}
            }
          }
        }
      }
    }

  }

  return "no solution exists";
}

console.log(solve24("4878"));

Add a Link to the page with the problem: https://www.freecodecamp.org/learn/coding-interview-prep/rosetta-code/24-game

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• Browser Name: Chrome
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• Operating System: Mac OS Catalina (10.15.4)

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[dostuffthatmatters]

@Sky020 Using eval is really unsafe!

The code executed from a string is being executed with the same priviliges as if the caller executed it using regular instructions. This would be a doorway for easier XSS attacks.

See the MDN Docs for details.

[ptkpyitheim]

@dostuffthatmatters Just made a pull request that has a checking that removes extra parentheses around single digits. I haven’t checked for situations like this though 1*2*(3*4) where there are extra parentheses in non-single digits