定義棧的數(shù)據(jù)結(jié)構(gòu)腰鬼,請在該類型中實現(xiàn)一個能夠得到棧中所含最小元素的min函數(shù)(時間復(fù)雜度應(yīng)為O(1))。
代碼
import java.util.Stack;
public class Solution{
Stack<Integer> dataStack = new Stack<Integer>();
Stack<Integer> minStack = new Stack<Integer>();
public void push (int value){
dataStack.push(value);
if(minStack.isEmpty() || value<minStack.peek()){
minStack.push(value);
}else{
minStack.push(minStack.peek());
}
}
public void pop(){
dataStack.pop();
minStack.pop();
}
public int top(){
return dataStack.peek();
}
public int min(){
return minStack.peek();
}
}
通過設(shè)置一個輔助棧minStack,與在dataStack中壓入得數(shù)據(jù)對比沛善。時刻保證top的peek是最小的。