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StackWithMin.java
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60 lines (52 loc) · 1.36 KB
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package stackqueue;
import java.util.Stack;
/**
* @Classname StackWithMin
* @Description TODO
* @Date 2019/7/2 21:43
* @Created by xww
*/
public class StackWithMin<T extends Comparable> {
private Stack<T> stackData = new Stack<>();
private Stack<T> stackMin = new Stack<>();
public void push(T data){
stackData.push(data);
if(stackMin.isEmpty()){
stackMin.push(data);
}else {
T temp = stackMin.peek();
if(temp.compareTo(data) > 0){
stackMin.push(data);
}else{
stackMin.push(temp);
}
}
}
public T pop(){
if(stackData.isEmpty())
return null;
stackMin.pop();
return stackData.pop();
}
public T min(){
if(stackMin.isEmpty())
return null;
return stackMin.peek();
}
public static void main(String[] args) {
StackWithMin<Integer> stack = new StackWithMin<>();
stack.push(3);
stack.push(4);
stack.push(2);
stack.push(1);
System.out.println(stack.min());
stack.pop();
System.out.println(stack.min());
stack.pop();
System.out.println(stack.min());
stack.pop();
System.out.println(stack.min());
stack.pop();
System.out.println(stack.min());
}
}