p5.js |快速排序

QuickSort 是一种分而治之的算法。它选择一个元素作为枢轴，并围绕选择的枢轴对给定数组进行分区。有许多不同版本的 quickSort 以不同的方式选择枢轴。

• 始终选择第一个元素作为枢轴。
• 始终选择最后一个元素作为枢轴。
• 选择一个随机元素作为枢轴。
• 选择中位数作为支点。

方法：

• 首先取一个随机值数组。
• 根据该数组索引处的值并排绘制矩形。
• 在 p5.js 中实现快速排序算法。
• 分配时间延迟，以便可视化每个连续阶段所做的更改。

例子：

  

    
      
    QuickSort Sorting Algorithm
      
    
      
     
        body {
            padding: 0;
            margin: 0;
        } 
        canvas {
            vertical-align: top;
        } 
    

  

    
          
        // Assign Global Values
        let values = [];
        let w = 20;
        let states = [];
        function setup() {
          
            // Create Canvas of given Size
            createCanvas(800, 500);
          
            // Assign Array of Random Values
            values = new Array(floor(width/w));
              
            for(let i = 0; i < values.length; i++) {
                values[i] = float(random(height));
                states[i] = -1; 
            }
              
            // To print values to Browser's Console
            print("Unsorted Array:" + values);
              
            // Invoke QuickSort Function
            quickSort(values, 0, values.length);
              
            print("Sorted Array:" + values);
        }
          
        // Asynchronous Definition of Quick Sort Function
        async function quickSort(arr, start, end) {
            if(start >= end) {
                return;
            }
            let index = await partition(arr, start, end);
            states[index] = -1;
              
            // Promise.all is used so that each function
            // should invoke simultaneously
            await Promise.all([quickSort(arr, start, index-1),
                    quickSort(arr, index+1, end)]);
        }
          
        // Asynchronous Definition of Partition Function
        async function partition(arr, start, end) {
              
            for(let i = start; i< end; i++) {
                states[i] = 1;
            }
              
            let pivotIndex = start;
            let pivotValue = arr[end];
            states[pivotIndex] = 0;
              
            for(let i = start; i < end; i++) {
                if(arr[i]<pivotValue) {
                    await swap(arr, i, pivotIndex);
                    states[pivotIndex] = -1;
                    pivotIndex++;
                    states[pivotIndex] = 0;
                }
            }
              
            await swap(arr, pivotIndex, end);
              
                for(let i = start; i < end; i++) {
                    states[i] = -1;
                }
              
            return pivotIndex;
        }
          
        // Definition of Draw function
        function draw() {
              
            // Set Background Color 
            background(51);
              
            for(let i = 0; i < values.length; i++) {
                stroke(0);
                fill(255);
                  
                if(states[i] == 0) {
                  
                    // Pivot Element
                    fill(255, 0, 0);
                }
                else if (states[i]==1) {
                    // Sorting bar
                    fill("#58FA82");
                }
                else {
                    // Sorted Bars
                    fill(255);
                }
                  
                rect(i*w, height - values[i], w, values[i]);
            }
        }
          
        async function swap(arr, a, b) {
              
            // Call to sleep function
            await sleep(100);
            let t = arr[a];
            arr[a] = arr[b];
            arr[b] = t;
        }
          
        // Definition of sleep function
        function sleep(ms) {
            return new Promise(resolve
                    => setTimeout(resolve, ms));
        }
    

  
                    

输出：