p5.js |堆栈中的弹出操作

堆栈是一种线性数据结构，它遵循执行操作的特定顺序。顺序可以是 LIFO（后进先出）或 FILO（先进后出）。

堆栈上的弹出操作：在将内容从堆栈顶部删除的同时访问内容，称为弹出操作。在 pop() 操作的数组实现中，数据元素实际上并没有被删除，而是将 top 递减到堆栈中的较低位置以指向下一个值。但在链表实现中，pop() 实际上会删除数据元素并释放内存空间。

方法： pop() 操作可能涉及以下步骤：

• 检查堆栈是否为空。
• 如果堆栈为空，则产生错误并退出。
• 如果堆栈不为空，则访问 top 指向的数据元素。
• 删除元素，对缓冲区使用 array.pop() 操作。
• 返回成功。

示例 1：此示例仅描述堆栈上的推送操作。

  

    Stack Data Structure
      
    
  
    
  
    
        body {
            padding: 0;
            margin: 0;
        } 
        canvas {
            vertical-align: top;
        } 
    

  

    
      
        // Define Stack function 
        function Stack(array) {
            this.array = [];
            if (array) this.array = array;
        }
          
        // Add Get Buffer property to object
        // constructor which slices the array
        Stack.prototype.getBuffer = function() {
            return this.array.slice();
        }
          
        // Add isEmpty properties to object
        // constructor which returns the
        // length of the array
        Stack.prototype.isEmpty = function() {
            return this.array.length == 0;
        }
          
        // Instance of the stack class
        var stack1 = new Stack(); //Stack { array: [] }
          
        // Add Push property to object constructor
        // which push elements to the array
        Stack.prototype.push = function(value) {
            this.array.push(value);
        }
          
        function setup() {
          
            // Create Canvas of size display width * 300
            createCanvas(displayWidth, 300);
        }
          
        function draw() {
              
            // Set background color
            background("grey");
              
            // Set stroke weight
            strokeWeight(3);
              
            // Set stroke color
            stroke('black');
            line(10, 45, 90, 45);
            rect(10, 30, 40, 30);
            noStroke();
            text("TOP", 20, 50);
              
            // Display stack 
            for(var i = stack1['array'].length-1; i >= 0; i--) {
                var p = 10;
                translate(70, 0);
                strokeWeight(3);
                stroke('black');
                line(10+p, 45, p+80, 45);
                noStroke();
                rect(10+p, 30, 40+p, 30);
                text(stack1['array'][i], 40, 50);
                p += 10;
            }
              
            textSize(16);
            text("Current Top : " + stack1.peek(), 0, 130); 
            textSize(13);
        }
          
        // Peek Function
        Stack.prototype.peek = function() {
            return this.array[this.array.length-1];
        }
          
        // Call to push operation
        stack1.push(1);
        stack1.push(2);
        stack1.push(3);
        stack1.push(19);
        stack1.push(11);
        stack1.push(12);
    

  
                         

输出：

示例 2：本示例通过调用stack1.pop()函数将元素压入堆栈后，使用了两次 Pop 操作。

  

    Stack Data Structure
      
    
  
    
  
    
        body {
            padding: 0;
            margin: 0;
        } 
        canvas {
            vertical-align: top;
        } 
    

  

    
      
        // Define Stack function 
        function Stack(array) {
            this.array = [];
            if (array) this.array = array;
        }
          
        // Add Get Buffer property to object
        // constructor which slices the array
        Stack.prototype.getBuffer = function() {
            return this.array.slice();
        }
          
        // Add isEmpty properties to object
        // constructor which returns the
        // length of the array
        Stack.prototype.isEmpty = function() {
            return this.array.length == 0;
        }
          
        // Instance of the stack class
        var stack1 = new Stack(); //Stack { array: [] }
          
        // Add Push property to object constructor
        // which push elements to the array
        Stack.prototype.push = function(value) {
            this.array.push(value);
        }
          
        function setup() {
          
            // Create Canvas of size display width * 300
            createCanvas(displayWidth, 300);
        }
          
        function draw() {
              
            // Set background color
            background("grey");
              
            // Set stroke weight
            strokeWeight(3);
              
            // Set stroke color
            stroke('black');
            line(10, 45, 90, 45);
            rect(10, 30, 40, 30);
            noStroke();
            text("TOP", 20, 50);
              
            // Display stack 
            for(var i = stack1['array'].length-1; i >= 0; i--) {
                var p = 10;
                translate(70, 0);
                strokeWeight(3);
                stroke('black');
                line(10+p, 45, p+80, 45);
                noStroke();
                rect(10+p, 30, 40+p, 30);
                text(stack1['array'][i], 40, 50);
                p += 10;
            }
              
            textSize(16);
            text("Current Top : " + stack1.peek(), 0, 130); 
            textSize(13);
        }
          
        // Peek Function
        Stack.prototype.peek = function() {
            return this.array[this.array.length-1];
        }
          
        // Pop operation
        Stack.prototype.pop = function() {
            return this.array.pop();
        }
          
        // Call to push operation
        stack1.push(1);
        stack1.push(2);
        stack1.push(3);
        stack1.push(19);
        stack1.push(11);
        stack1.push(12);
          
        // Call to pop operation
        stack1.pop();
        stack1.pop();
    

  
                        

输出：