@TOC
# 一、打乱数组  ```java class Solution { int[] nums; // 用以打乱的数组 int[] tempArr; public Solution(int[] nums) { this.nums = nums.clone(); tempArr = nums.clone(); } public int[] reset() { return nums; } // 随机两两互换进行打乱 public int[] shuffle() { int r1 = new Random().nextInt(nums.length); int r2 = new Random().nextInt(nums.length); int temp = tempArr[r1]; tempArr[r1] = tempArr[r2]; tempArr[r2] = temp; return tempArr; } } ```
# 二、最小栈  ```java class MinStack { //链表头，相当于栈顶 private ListNode head; //压栈，需要判断栈是否为空 public void push(int x) { if (empty()) { head = new ListNode(x, x, null); } else { head = new ListNode(x, Math.min(x, head.min), head); } } //出栈，相当于把链表头删除 public void pop() { if (empty()) { throw new IllegalStateException("Stack is Empty"); } head = head.next; } //栈顶的值也就是链表头的值 public int top() { if (empty()) { throw new IllegalStateException("Stack is Empty"); } return head.val; } //链表中头结点保存的是整个链表最小的值，所以返回head.min也就是 //相当于返回栈中最小的值 public int getMin() { if (empty()) { throw new IllegalStateException("Stack is Empty"); } return head.min; } //判断栈是否为空 private boolean empty() { return head == null; } } class ListNode { public int val; public int min;//最小值 public ListNode next; public ListNode(int val, int min, ListNode next) { this.val = val; this.min = min; this.next = next; } } ```
