two-prisoners-count-trees

two-prisoners-count-trees.js

var options = {
  smaller: 18,
  bigger: 20,
};
var northInferSouthMin;
var southInferNorthMax;

function northAnswer (trees) {
  northInferSouthMin = options.bigger - southInferNorthMax;
  // console.log('  northInferSouthMin', northInferSouthMin);

  var sumMin = northInferSouthMin + trees;

  if (sumMin >= options.bigger) {
    // console.log('  North answer', options.bigger);
    return options.bigger;
  } else {
    // console.log('  North don\'t answer');
    return null;
  }
}

function southAnswer (trees) {
  southInferNorthMax = options.smaller - northInferSouthMin;
  // console.log('  southInferNorthMax', southInferNorthMax);

  var sumMax = southInferNorthMax + trees;

  if (sumMax <= options.smaller) {
    // console.log('  South answer', options.smaller);
    return options.smaller;
  } else {
    // console.log('  South don\'t answer');
    return null;
  }
}

function dayByday(northTrees, southTrees) {
  var sum = northTrees + southTrees;

  northInferSouthMin = 0;
  southInferNorthMax = options.bigger;

  for (var i = 1; ;i++) {
    // console.log('Day', i);
    switch (northAnswer(northTrees)) {
      case sum:
        return true;
      case null:
        // Nothing happen
        break;
      default:
        return false;
    }

    switch (southAnswer(southTrees)) {
      case sum:
        return true;
      case null:
        // Nothing happen
        break;
      default:
        return false;
    }
  }
}

for (var i = 0; i <= options.smaller; i++) {
  if (!dayByday(i, options.smaller-i)) {
    console.log('fail on', i, options.smaller-i);
  } else {
    console.log('pass', i, options.smaller-i);
  };
}

for (var i = 0; i <= options.bigger; i++) {
  if (!dayByday(i, options.bigger-i)) {
    console.log('fail on', i, options.bigger-i);
  } else {
    console.log('pass', i, options.bigger-i);
  };
}