ArithGeo.mdown

ArithGeo() Three Different Solutions

With A Pattern Detection Callback Function

function ArithGeo(arr){
  function isPattern(arr, pTest){
    var factor = 0, match = true, i;

    for (i = 0; i < arr.length -1 && match; i++) {
      if (i === 0) {
        factor = pTest( arr[i], arr[i+1] );
      } else if ( factor !== pTest( arr[i], arr[i+1] )) {
        match = false
      } };
    return match;
  };
  while ( arr && arr.length > 2 ) {
    return ( isPattern( arr, (a,b) => a - b )) ? 'Arithmetic' :
              ( isPattern( arr, (a,b) => b/a )) ? "Geometric" : -1
  };
}

What's Going on Here

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With Reduce

function ArithGeo(arr){
  
  function arith(arr){
    var dif = arr[1] - arr[0];
    return arr.reduce(( pre, cur, i, ray ) =>
      (pre) ? (dif === ( ray[i] - ray[i-1] )) :false );
  }

  function geo(arr){
     var div = arr[1] / arr[0];
     return arr.reduce(( pre, cur, i, ray ) =>
      (pre) ? (div === ( ray[i] / ray[i-1] )) :false );
  }

  return ( arith( arr)) ? "Arithmetic" :
   ( geo( arr)) ? "Geometric" : -1;
}

What's Going on Here

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With For Loops

function ArithGeo(arr) {
var dif = arr[1]-arr[0],
div = arr[1]/arr[0], arith, geo, i;

  for (i=0; i<arr.length-1; i++){
    if (dif + arr[i] === arr[i+1]){
      arith = true;
    } else {
      arith = false;
      break;
    }
  }
  for (i=0; i<arr.length-1; i++){
    if (div * arr[i] === arr[i+2]) {
      geo = true;
    } else {
      geo = false;
    }
  }
  if (arith === true) {
      return "Arithmetic";
    } else if (geo === true) {
      return "Geometric";
    } else {
      return -1;
    }
}

What's Going on Here

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