Step by Step solution about How to resolve the algorithm Sorting algorithms/Patience sort step by step in the JavaScript programming language

This JavaScript code implements the Patience Sorting algorithm, also known as the Build-a-Pile algorithm, to sort an array of numbers in ascending order. It follows these steps:

1. Initialize empty piles (an array of arrays).

2. Iterate through the input array and for each element:

   • Find the destination pile where the element can be placed, ensuring that it is greater than or equal to the previous element in the pile.
   • If no suitable pile is found, create a new pile with the element.

3. After placing all elements in the piles, merge the piles back into the input array in sorted order.

   • Find the pile with the smallest top element.
   • Move the top element of that pile to the output array.
   • If the pile is now empty, remove it.

4. Repeat step 3 until all piles are merged.

The provided example sorts the array [10,6,-30,9,18,1,-20] using the Patience Sort algorithm. The result is [-30,-20,1,6,9,10,18], which is the sorted version of the input array.

The provided JavaScript code implements a Patience Sort algorithm, which arranges a given array of integers (nums) into sorted order in a specific manner. Here's a detailed explanation of the code:

1. Initialization:

   • An empty array called piles is created to store piles (lists) of integers. Each pile represents a sorted sequence of numbers.

2. Populating Piles:

   • The code iterates through each number (num) in the nums array using a for loop.
   • For each number:
     • It finds the destination pile index (destinationPileIndex) where num can be placed in ascending order using the findIndex method.
     • If a suitable pile is found for num, it is pushed onto that pile.
     • Otherwise, a new pile is created containing just num.

3. Extracting Sorted Elements:

   • After populating the piles, a second for loop iterates through the indices of the original nums array.
   • In each iteration, it finds the pile with the smallest top element (destinationPileIndex) among all the piles.
   • The top element of the destination pile is removed (shift()) and assigned to the corresponding index in the nums array.
   • If the destination pile becomes empty after the removal, it is removed from the piles array using splice().

4. Final Result:

   • This process continues until all numbers have been placed in the nums array in sorted order.
   • Finally, the sorted nums array is returned as the result.

5. Example Usage:

   • At the end of the code, an example array, [10, 6, -30, 9, 18, 1, -20], is passed to the patienceSort function, and the sorted result is printed to the console.

In summary, Patience Sort operates by building piles of sorted numbers, where each pile represents a descending sequence. The algorithm then iteratively extracts the smallest top element from the piles, placing them in the correct order in the original array. This results in a sorted array while maintaining the relative order of numbers within each pile.

const patienceSort = (nums) => {
  const piles = []

  for (let i = 0; i < nums.length; i++) {
    const num = nums[i]
    const destinationPileIndex = piles.findIndex(
      (pile) => num >= pile[pile.length - 1]
    )
    if (destinationPileIndex === -1) {
      piles.push([num])
    } else {
      piles[destinationPileIndex].push(num)
    }
  }

  for (let i = 0; i < nums.length; i++) {
    let destinationPileIndex = 0
    for (let p = 1; p < piles.length; p++) {
      const pile = piles[p]
      if (pile[0] < piles[destinationPileIndex][0]) {
        destinationPileIndex = p
      }
    }
    const distPile = piles[destinationPileIndex]
    nums[i] = distPile.shift()
    if (distPile.length === 0) {
      piles.splice(destinationPileIndex, 1)
    }
  }

  return nums
}
console.log(patienceSort([10,6,-30,9,18,1,-20]));