swe_interview_questions

interview.md

onlyOne

Write a function that returns true or false if exactly one of its parameter is true.

const a = true;
const b = false;
const c = false;
...
onlyOne(a, b, b);  // true
onlyOne(a, b, b, b);  // true
onlyOne(b, b, c, c);  // false
onlyOne(a, b, b, c);  //false
onlyOne(a, a, b);  // false

Solution

const onlyOne() => {
  let sum = 0;
  arguments.forEach((argument) => {
    if (argument) {
      sum += Number(!!argument);
    }
  });
  return sum === 1;
}

Similarly, we can extend implementations for onlyTwo and onlyFive etc by changing the last return check, i.e. sum === n;