dashing-hyacinth-2585

readme.md

dashing-hyacinth-2585

Created with <3 with dartpad.dev.

main.dart

import 'dart:math';

/// Block Party Technical Exercise using Dart
/// By Ross Llewallyn
/// Completed in about 45 minutes
///
/// Run (assuming you have Dart on your machine) using: `dart maxPairTest.dart`
/// Run on DartPad here: https://dartpad.dev/?id=c85169d3058f229a27edc250a063fecc
/// GitHub Gist here: https://gist.github.com/EnduringBeta/c85169d3058f229a27edc250a063fecc

/// Dart doesn't current have a Tuple type, so custom class used.
class Pair {
  Pair(this.first, this.second);

  final int first;
  final int second;

  @override
  String toString() {
    return "($first, $second)";
  }
}

/// Thoughts:
/// * it seems like the second index isn't actually needed since it will always
///   be the first + 1.
/// * can't just look for largest value; see examples
/// * don't store list the size of input
void main() {
  /// Output the indices of the two consecutive elements that have the highest
  /// max sum in an input array of integers (e.g., maxPair([0, 5, 5, 2]) will
  /// return (1, 2)).
  ///
  /// In the case of a tie, the method should return the leftmost pair
  /// (e.g., maxPair([0, 4, 3, 1, 2, 3, 4, 0]) will return (1, 2)).
  Pair? maxPair(List<int> list) {
    // No directions given on how to handle small lists, so returning null,
    // which seems better than a false (0, 0) or something
    if (list.length < 2) {
      return null;
    }

    int highestPair = 0;
    int highestPairIndex = 0;

    list.asMap().forEach((int index, int value) {
      // Skip last item
      if (index != list.length - 1) {
        // We can trust index + 1 exists, so get sum
        final int sum = list[index + 1] + value;

        // If found new highest value, keep it and the index where found
        if (sum > highestPair) {
          highestPair = sum;
          highestPairIndex = index;
        }
      }
    });

    // Return highest value's index and the next index
    return Pair(highestPairIndex, highestPairIndex + 1);
  }

  // Basic example
  print(maxPair([1, 2, 3]));
  // Instruction examples
  print(maxPair([0, 5, 5, 2]));
  print(maxPair([0, 4, 3, 1, 2, 3, 4, 0]));
  // Bad examples
  print(maxPair([]));
  print(maxPair([99]));
  // Example where highest # isn't part of answer
  print(maxPair([9, 1, 8, 3, 5]));
  // Repetitive, long list
  print(maxPair([1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 2]));
  // Super long list
  print(maxPair(List.generate(1000, (_) => Random().nextInt(100))));
}