力扣刷题前置Java语法

String类

s.length()
s.charAt(i)
s.substring(a, b)
s.equals(t)

Array类

nums.length
Arrays.sort(nums)
Arrays.toString(nums)

ArrayList

list.add(x)
list.get(i)
list.remove(i)
list.size()
list.contains(x)

HashMap

map.put(key, value)
map.get(key)
map.containsKey(key)
map.remove(key)
map.size()

HashSet

set.add(x)
set.contains(x)
set.remove(x)
set.size()

Queue

queue.offer(x)
queue.poll()
queue.peek()

Stack

Deque<Integer> stack = new ArrayDeque<>();

stack.push(x);
stack.pop();
stack.peek();