cielux
10/15/2018 - 5:42 AM

Can Two Movies Fill Flight

Build a feature for choosing two movies whose total runtimes will equal the exact flight length.

Write a function that takes an integer flightLength (in minutes) and an array of integers movieLengths (in minutes) and returns a boolean indicating whether there are two numbers in movieLengths whose sum equals flightLength.

canTwoMoviesFillFlight.js
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function canTwoMoviesFillFlight(movieLengths, flightLength) {
  // Determine if two movie runtimes add up to the flight length
  let lengthMap = {};
  for (let i = 0; i < movieLengths.length; i++) {
    if (lengthMap[movieLengths[i]]) {
      return true;
    } else {
      lengthMap[flightLength - movieLengths[i]] = movieLengths[i];
    }
  }

  return false;
}

// Tests

let desc = 'short flight';
let actual = canTwoMoviesFillFlight([2, 4], 1);
let expected = false;
assertEquals(actual, expected, desc);

desc = 'long flight';
actual = canTwoMoviesFillFlight([2, 4], 6);
expected = true;
assertEquals(actual, expected, desc);

desc = 'one movie half flight length';
actual = canTwoMoviesFillFlight([3, 8], 6);
expected = false;
assertEquals(actual, expected, desc);

desc = 'two movies half flight length';
actual = canTwoMoviesFillFlight([3, 8, 3], 6);
expected = true;
assertEquals(actual, expected, desc);

desc = 'lots of possible pairs';
actual = canTwoMoviesFillFlight([1, 2, 3, 4, 5, 6], 7);
expected = true;
assertEquals(actual, expected, desc);

desc = 'not using first movie';
actual = canTwoMoviesFillFlight([4, 3, 2], 5);
expected = true;
assertEquals(actual, expected, desc);

desc = 'only one movie';
actual = canTwoMoviesFillFlight([6], 6);
expected = false;
assertEquals(actual, expected, desc);

desc = 'no movies';
actual = canTwoMoviesFillFlight([], 2);
expected = false;
assertEquals(actual, expected, desc);

function assertEquals(a, b, desc) {
  if (a === b) {
    console.log(`${desc} ... PASS`);
  } else {
    console.log(`${desc} ... FAIL: ${a} != ${b}`);
  }
}