155.minStack.go

package mystack

import"Leetcode/algorithms/kit"

// MinStack declare
typeMinStackstruct {
data*Stack// 数据栈
helper*Stack// 辅助栈
}

// NewMinStack returns MinStack constructor
funcNewMinStack() *MinStack {
return&MinStack{
data: kit.NewStack(),
helper: kit.NewStack(),
 }
}

// key1: 辅助栈的元素空的时候，必须放入新进来的数
// key2: 新来的数小于或者等于辅助栈栈顶元素的时候，才放入
// key3: 出栈时，辅助栈的栈顶元素等于数据栈的栈顶元素，才出栈，即"出栈保持同步"
func (s*MinStack) Push(xint) {
s.data.Push(x)
ifs.helper.IsEmpty() || (s.helper.Peek()).(int) >=x {
s.helper.Push(x)
 }
}

// Pop pop the top ele of stack
func (s*MinStack) Pop() {
if!s.data.IsEmpty() {
top:=s.data.Pop()
iftop==s.helper.Peek() {
s.helper.Pop()
 }
 }
}

// Top returns the top ele of stack, not modify internal struct
func (s*MinStack) Top() int {
if!s.data.IsEmpty() {
return (s.data.Peek()).(int)
 }
panic("Illegal operation Top(), stack is empty")
}

// GetMin returns the minimum ele of stack
func (s*MinStack) GetMin() int {
if!s.helper.IsEmpty() {
return (s.helper.Peek()).(int)
 }
panic("Illegal operation GetMin(), stack is empty")
}