数据结构----栈

// 栈

/*
* 栈被称为一种后入先出（LIFO，last-in-first-out）的数据结构。
*
* push : 入栈
* pop: 出栈
* top: 栈顶位置 初始化为0 表示栈顶对应数组的起始位置 0  1--》对应数组第一个元素  top-1  就是栈顶元素
  peek: 预览栈顶的元素 不从栈中删除
  clear: 清除栈中的元素 
 * */

function push(element) {
    this.dataStore[this.top++] = element;
}
function pop() {
    return this.dataStore[--this.top];
}
function peek() {
    return this.dataStore[this.top - 1];
}
function length() {
    return this.top;
}
function clear() {
    this.top = 0;
}
function Stack() {
    this.dataStore = [];
    this.top = 0;
    this.push = push;
    this.pop = pop;
    this.peek = peek;
    this.length = length;
    this.clear = clear;
}

// var s = new Stack();
//
// s.push("David");
// s.push("Raymond");
// s.push("Bryan");
//
// console.log(s.length(),s.peek())

//列子  转化进制

function mulBase(num,base) {
    var s = new Stack();
    do {
        s.push(num % base);
        num = Math.floor(num /= base);
    }while (num > 0);

    var converted = "";

    while (s.length() > 0) {
        converted += s.pop();
    }
    return converted;
}

console.log(mulBase(32,2));

//判断是否是回文

function isPalindrome(word) {
    var s = new Stack();
    word = word.toString();
    for(var i = 0 ; i< word.length;i++) {
        s.push(word[i]);
    }
    var rword = "";
    while (s.length() > 0) {
        rword += s.pop();
    }
    return word === rword;
}

console.log(isPalindrome(1011));


//模拟递归

function fact(num) {
    var s = new Stack();
    for(var i = num; i >= 1; i--) {
      s.push(i);
    }
    var product = 1;
    while (s.length() > 0) {
        product *= s.pop();
    }
    return product;
}
console.log(fact(5));