Array merge sort - Node.js Algorithm

Node.js examples for Algorithm:Sort

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Description

Array merge sort

Demo Code

function mergesortSingle( array ) {
  var mid = Math.floor( array.length / 2 );
  var left = array.slice(0, mid);
  var right = array.slice(mid);
  if( left.length > 1 ) left = mergesort( left );
  if( right.length  > 1 ) right = mergesort( right );

  result = [];//from w w w .  j a v  a 2s  .  c om
  while( left.length && right.length ) {
    if( left[left.length - 1 ] > right[ right.length - 1 ] ) {
      result.push( left.pop() )
    } else {
      result.push( right.pop() );
    }
  }

  result.reverse();
  if( left.length ) return left.concat( result );
  else return right.concat(result);
}

var unsortedA = [];
var unsortedB = [];
for(var i = 0; i < 2000000; ++i) {
  unsortedA.push( Math.round( Math.random() * 2000 ) );
  // unsortedB.push( Math.round( Math.random() * 2000 ) );
}
unsortedB = unsortedA.concat();

var start = Date.now();
unsortedB.sort();
var end = Date.now();
console.log("RegSort = " , end-start );

var start = Date.now();
// unsortedA.mergesort()
unsortedA = mergesort( unsortedA );

var end = Date.now();
console.log("MergeSort = " , end-start);

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