Sorting Algorithm Animations

There are many sorting algorithms, each has its own advantages and limitations.

Sorting is commonly used as the introductory problem in various Computer Science classes to showcase a range of algorithmic ideas.

Here are some examples of algorithms applied on arrays of integers and their animation to visualize how they work.

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 1. Bubble Sort

Time complexity : O(n²)

Algorithm:

function bubbleSort(arr) {
	var len = arr.length;
	for (var i = len - 1; i >= 0; i--) {
		for (var j = 1; j <= i; j++) {
			if (arr[j - 1] > arr[j]) {
				var temp = arr[j - 1];
				arr[j - 1] = arr[j];
				arr[j] = temp;
			}
		}
	}
	return arr;
}

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 2. Selection Sort

Time complexity : O(n²)

Algorithm:

function selectionSort(arr){
  var minIdx, temp, 
      len = arr.length;
  for(var i = 0; i < len; i++){
    minIdx = i;
    for(var  j = i+1; j<len; j++){
       if(arr[j]<arr[minIdx]){
          minIdx = j;
       }
    }
    temp = arr[i];
    arr[i] = arr[minIdx];
    arr[minIdx] = temp;
  }
  return arr;
}

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 3. Merge Sort

Time complexity : O(n*log n)

Algorithm:

function mergeSort(arr){
   var len = arr.length;
   if(len <2)
      return arr;
   var mid = Math.floor(len/2),
       left = arr.slice(0,mid),
       right =arr.slice(mid);
   return merge(mergeSort(left),mergeSort(right));
}
        
function merge(left, right){
  var result = [],
      lLen = left.length,
      rLen = right.length,
      l = 0,
      r = 0;
  while(l < lLen && r < rLen){
     if(left[l] < right[r]){
       result.push(left[l++]);
     }
     else{
       result.push(right[r++]);
    }
  }  
  return result.concat(left.slice(l)).concat(right.slice(r));
}

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 4. Quick Sort

Time complexity : O(n*log n)

Algorithm:

function quickSort(arr, left, right){
   var len = arr.length, 
   pivot,
   partitionIndex;


  if(left < right){
    pivot = right;
    partitionIndex = partition(arr, pivot, left, right);
    
   //sort left and right
   quickSort(arr, left, partitionIndex - 1);
   quickSort(arr, partitionIndex + 1, right);
  }
  return arr;
}
        

function partition(arr, pivot, left, right){
   var pivotValue = arr[pivot],
       partitionIndex = left;

   for(var i = left; i < right; i++){
    if(arr[i] < pivotValue){
      swap(arr, i, partitionIndex);
      partitionIndex++;
    }
  }
  swap(arr, right, partitionIndex);
  return partitionIndex;
}
        

function swap(arr, i, j){
   var temp = arr[i];
   arr[i] = arr[j];
   arr[j] = temp;
}