数据结构算法注意点⚠️

目录

• 二分查找
• 链表

二分查找

mid = low + (low + high)/2;
//这样可以防止越界

链表

1. 反转

1.1 迭代

ListNode pre = null, cur = head, next = null;
whilt(cur != null){
	next = cur.next;
	cur.next = pre;
	pre = cur;
	cur = next;
}

1.2 递归

	ListNode newHead = reverseList(head.next);
	head.next.next = head;
	head.next = null;
	return newHead;

2. 复制

2.1 迭代

Map<Node, Node> cachedNode = new HashMap<Node, Node>();

public Node copyRandomList(Node head) {
	if (head == null) {
		return null;
	}
	if (!cachedNode.containsKey(head)) {
		Node headNew = new Node(head.val);
		cachedNode.put(head, headNew);
		headNew.next = copyRandomList(head.next);
		headNew.random = copyRandomList(head.random);
	}
	return cachedNode.get(head);
}