История изменений

const expectedValue = 200;

const digits = ['9', '8', '7', '6', '5', '4', '3', '2', '1', '0'];
const operations = ['', '+', '-'];
const permutation = new Uint8Array(digits.length - 1).fill(0);
do {
  const expressionChars = [];
  for (let i = 0; i < digits.length - 1; i++) {
    expressionChars.push(digits[i]);
    expressionChars.push(operations[permutation[i]]);
  }
  expressionChars.push(digits[digits.length - 1]);
  const expressionString = expressionChars.join('');
  const expressionValue = eval(expressionString);
  if (expressionValue === expectedValue) console.log(expressionString);
} while (nextPermutation(permutation, operations.length));


function nextPermutation(permutation, cardinality) {
  let i = permutation.length - 1;
  while (i >= 0 && permutation[i] === cardinality - 1) {
    permutation[i] = 0;
    i--;
  }
  if (i < 0) return false;
  permutation[i]++;
  return true;
}

const expectedValue = 200;

const digits = ['9', '8', '7', '6', '5', '4', '3', '2', '1', '0'];
const operations = ['', '+', '-'];
const permutation = new Uint8Array(digits.length - 1).fill(0);
do {
  const expressionChars = [];
  for (let i = 0; i < digits.length - 1; i++) {
    expressionChars.push(digits[i]);
    expressionChars.push(operations[permutation[i]]);
  }
  expressionChars.push(digits[digits.length - 1]);
  const expressionString = expressionChars.join('');
  const expressionValue = eval(expressionString);
  if (expressionValue === expectedValue) {
    console.log(expressionString);
  }
} while (nextPermutation(permutation, operations.length));


function nextPermutation(permutation, cardinality) {
  let i = permutation.length - 1;
  while (i >= 0 && permutation[i] === cardinality - 1) {
    permutation[i] = 0;
    i--;
  }
  if (i < 0) return false;
  permutation[i]++;
  return true;
}