GUI(Graphical User Interface) helps in better understanding than programs. In this article, we will visualize Quick Sort using JavaScript. We will see how the array is being partitioned into two parts and how we get the final sorted array. We will also visualize the time complexity of Quick Sort.
Reference:
Approach:
- First, we will generate a random array using Math.random() function.
- Different colors are used to indicate which elements are compared, left partition and right partition.
- Since the algorithm performs the operation very fast, the setTimeout() function has been used to slow down the process.
- New array can be generated by pressing the “Ctrl+R” key.
- The sorting is performed using QuickSort() function using hoare_partition() function
Example:
Before Sorting
After Sorting
Below is the program to visualize the Quick Sort algorithm.
index.html
<!DOCTYPE html> <html lang="en"> <head> <link rel="stylesheet" href="style.css" /> </head> <body> <br /> <p class="header">Quick Sort (Hoare's Partition)</p> <div id="array"></div> <div id="count"></div> <br /> <h2 class="range" style="text-align: center"></h2> <script src="script.js"></script> </body> </html> |
style.css
* { margin: 0px; padding: 0px; box-sizing: border-box; } .header { font-size: 20px; text-align: center; } #array { background-color: white; height: 288px; width: 598px; margin: auto; position: relative; margin-top: 64px; } .block { width: 28px; background-color: #6b5b95; position: absolute; bottom: 0px; transition: 0.2s all ease; } .block_id { position: absolute; color: black; margin-top: -20px; width: 100%; text-align: center; } .block_id2 { position: absolute; color: black; margin-top: 22px; width: 100%; text-align: center; } .block2 { width: 28px; background-color: darkgray; position: absolute; transition: 0.2s all ease; } .block_id3 { position: absolute; color: black; margin-top: 1px; width: 100%; text-align: center; } #count { height: 20px; width: 598px; margin: auto; } |
script.js
var container = document.getElementById("array"); // Function to generate the array of blocks function generatearray() { for (var i = 0; i < 20; i++) { // Return a value from 1 to 100 (both inclusive) var value = Math.ceil(Math.random() * 100); // Creating element div var array_ele = document.createElement("div"); // Adding class 'block' to div array_ele.classList.add("block"); // Adding style to div array_ele.style.height = `${value * 3}px`; array_ele.style.transform = `translate(${i * 30}px)`; // Creating label element for displaying // size of particular block var array_ele_label = document.createElement("label"); array_ele_label.classList.add("block_id"); array_ele_label.innerText = value; // Appending created elements to index.html array_ele.appendChild(array_ele_label); container.appendChild(array_ele); } } // Function to generate indexes var count_container = document.getElementById("count"); function generate_idx() { for (var i = 0; i < 20; i++) { // Creating element div var array_ele2 = document.createElement("div"); // Adding class 'block2' to div array_ele2.classList.add("block2"); // Adding style to div array_ele2.style.height = `${20}px`; array_ele2.style.transform = `translate(${i * 30}px)`; //adding indexes var array_ele_label2 = document.createElement("label"); array_ele_label2.classList.add("block_id3"); array_ele_label2.innerText = i; // Appending created elements to index.html array_ele2.appendChild(array_ele_label2); count_container.appendChild(array_ele2); } } async function hoare_partition(l, r, delay = 700) { var blocks = document.querySelectorAll(".block"); var pivot = Number(blocks[l].childNodes[0].innerHTML); var i = l - 1; var j = r + 1; while (true) { // Find leftmost element greater than // or equal to pivot do { i++; if (i - 1 >= l) blocks[i - 1].style.backgroundColor = "red"; blocks[i].style.backgroundColor = "yellow"; //To wait for 700 milliseconds await new Promise((resolve) => setTimeout(() => { resolve(); }, delay) ); } while (Number(blocks[i].childNodes[0].innerHTML) < pivot); // Find rightmost element smaller than // or equal to pivot do { j--; if (j + 1 <= r) blocks[j + 1].style.backgroundColor = "green"; blocks[j].style.backgroundColor = "yellow"; //To wait for 700 milliseconds await new Promise((resolve) => setTimeout(() => { resolve(); }, delay) ); } while (Number(blocks[j].childNodes[0].innerHTML) > pivot); // If two pointers met. if (i >= j) { for (var k = 0; k < 20; k++) blocks[k].style.backgroundColor = "#6b5b95"; return j; } //swapping ith and jth element var temp1 = blocks[i].style.height; var temp2 = blocks[i].childNodes[0].innerText; blocks[i].style.height = blocks[j].style.height; blocks[j].style.height = temp1; blocks[i].childNodes[0].innerText = blocks[j].childNodes[0].innerText; blocks[j].childNodes[0].innerText = temp2; //To wait for 700 milliseconds await new Promise((resolve) => setTimeout(() => { resolve(); }, delay) ); } } // Asynchronous QuickSort function async function QuickSort(l, r, delay = 100) { // QuickSort Algorithm if (l < r) { //Storing the index of pivot element after partition var pivot_idx = await hoare_partition(l, r); //Recursively calling quicksort for left partition await QuickSort(l, pivot_idx); //Recursively calling quicksort for right partition await QuickSort(pivot_idx + 1, r); } } // Calling generatearray function generatearray(); // Calling generate_idx function generate_idx(); // Calling QuickSort function QuickSort(0, 19); |
Output:
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