剑指 Offer 30. 包含min函数的栈
难度简单
定义栈的数据结构,请在该类型中实现一个能够得到栈的最小元素的 min 函数在该栈中,调用 min、push 及 pop 的时间复杂度都是 O(1)。
示例:
MinStack minStack = new MinStack(); minStack.push(-2); minStack.push(0); minStack.push(-3); minStack.min(); —> 返回 -3. minStack.pop(); minStack.top(); —> 返回 0. minStack.min(); —> 返回 -2.
提示:
- 各函数的调用总次数不超过 20000 次
/**
* initialize your data structure here.
*/
var MinStack = function() {
//x_stack用来存储新的数据
//min_stack用来存储每一位数据对应的状态下的最小值
this.x_stack = []
this.min_stack = [Infinity]
};
/**
* @param {number} x
* @return {void}
*/
MinStack.prototype.push = function(x) {
this.x_stack.push(x)
this.min_stack.push(Math.min(this.min_stack[this.min_stack.length-1],x))
};
/**
* @return {void}
*/
MinStack.prototype.pop = function() {
this.x_stack.pop()
this.min_stack.pop()
};
/**
* @return {number}
*/
MinStack.prototype.top = function() {
return this.x_stack[this.x_stack.length-1]
};
/**
* @return {number}
*/
MinStack.prototype.min = function() {
return this.min_stack[this.min_stack.length-1]
};
/**
* Your MinStack object will be instantiated and called as such:
* var obj = new MinStack()
* obj.push(x)
* obj.pop()
* var param_3 = obj.top()
* var param_4 = obj.min()
*/