LeetCode 12.10（剑指offer）

*9 用栈实现队列

var CQueue = function() {
    this.stack0 = [];
    this.stack1 = [];
};

/** 
 * @param {number} value
 * @return {void}
 */
CQueue.prototype.appendTail = function(value) {
    while(this.stack1.length!==0){
        this.stack0.push(this.stack1.pop())
    }
    this.stack0.push(value);
};

/**
 * @return {number}
 */
CQueue.prototype.deleteHead = function() {
    if(this.stack0.length===0) return -1;
    while(this.stack0.length!==0){
        this.stack1.push(this.stack0.pop());
    }
    let res = this.stack1.pop();
    while(this.stack1.length!==0){
        this.stack0.push(this.stack1.pop())
    }
    return res;
};

30.包含min函數的栈

var MinStack = function() {
    this.stack = [];
    this.min_stack = [];
};

/** 
 * @param {number} x
 * @return {void}
 */
MinStack.prototype.push = function(x) {
    this.stack.push(x);
    if(this.min_stack.length===0) this.min_stack.push(x);
    else {
        this.min_stack.push(Math.min(this.min_stack[this.min_stack.length-1],x));
    }
};

/**
 * @return {void}
 */
MinStack.prototype.pop = function() {
    this.stack.pop();
    this.min_stack.pop();
};

/**
 * @return {number}
 */
MinStack.prototype.top = function() {
    return this.stack[this.stack.length-1];
};

/**
 * @return {number}
 */
MinStack.prototype.min = function() {
    return this.min_stack[this.min_stack.length-1]
};

06.从尾到头打印链表

var reversePrint = function(head) {
    let res = [];
    while(head!==null){
        res.unshift(head.val);
        head = head.next;
    }
    return res;
};

24.翻转链表

var reverseList = function(head) {
    if(head===null||head.next===null) return head;
    return reverse(null, head);
};
var reverse = (pre, next)=>{
    if(next===null) return pre;
    let tmp = next.next;
    next.next = pre;
    return reverse(next, tmp);
}