leetcode/MinStack.java at master · tinycedar/leetcode · GitHub

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import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

/**

* @author qienl

public class MinStack {

private int size;

private Node head = null;

private Integer min = null;

private class Node {

int value;

Node next;

public Node(int value, Node next) {

this.value = value;

this.next = next;

}

public MinStack() {

}

public void push(int x) {

this.size++;

this.head = new Node(x, this.head);

if (this.min == null || x < this.min) {

this.min = x;

}

public void pop() {

if (head != null) {

size--;

int top = head.value;

head = head.next;

if (head == null) {

this.min = null;

} else if (min != null && top == min) {

List<Integer> tempList = new ArrayList<>(this.size);

for (Node temp = head; temp != null; temp = temp.next) {

if (min == temp.value) {

return;

}

tempList.add(temp.value);

}

Collections.sort(tempList);

this.min = tempList.get(0);

}

public int top() {

if (head != null) {

return head.value;

}

throw new RuntimeException("Empty stack");

}

public int getMin() {

if (head != null && min != null) {

return this.min;

}

throw new RuntimeException("Empty stack");

}

public static void main(String[] args) {

MinStack obj = new MinStack();

obj.push(-2);

obj.push(0);

obj.push(-3);

obj.getMin();

obj.pop();

obj.top();

System.out.println(obj.getMin());

}

leetcode/MinStack.java at master · tinycedar/leetcode · GitHub

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