cgcardona

Sorting an array of integers

In javascript so that odd numbers are on the left and even numbers are on the right:

window.onload = function(){
  function sortArr(theArray){

    var leftPointer = 0;
    var rightPointer = theArray.length - 1;

    while(leftPointer < rightPointer) {

      if(((theArray[leftPointer] % 2) !== 0) && ((theArray[rightPointer] % 2) !== 0)){
        leftPointer++;
      }   
      else if(((theArray[leftPointer] % 2) === 0) && ((theArray[rightPointer] % 2) !== 0) || ((theArray[leftPointer] % 2) === 0) && ((theArray[rightPointer] % 2) === 0)){

        var tmp1 = theArray[leftPointer];
        var tmp2 = theArray[rightPointer];

        theArray[leftPointer] = tmp2;
        theArray[rightPointer] = tmp1;
      }   
      else{
        rightPointer--;
      }   
    }   

    return theArray;
  }
  console.log(sortArr([1,2,3,4,5,6]));
  // returns [1, 5, 3, 4, 2, 6] 
};

Mike Sealand came along with the following and destroyed me with regards to LOC. Also nice use of .reduce and .concat

window.onload = function(){
  function sortArr(theArray) {
    var separatedArrays = theArray.reduce(function(result, value) {
      result[value%2].push(value);
      return result;
    }, [[],[]]);
    return separatedArrays[1].concat(separatedArrays[0]);
  }

  console.log(sortArr([1,2,3,4,5,6]));
  // returns [1, 3, 5, 2, 4, 6] 
};

@omniegg weighed in with the following if you have underscore.js:

window.onload = function(){
    console.log(_.sortBy([1,2,3,4,5], function(n){ return n%2 }));
};

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Published

12 February 2013

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