내용이 점점 어려워진다. 완벽하게 이해하고 넘어가지 못하는 날도 있었지만 여전히 재밌다. 연습의 반복을 수 없이 해야겠다.
수면을 평소보다 덜 취하지만 바쁘게 살고있는 요즘이 즐겁다.
class Node:
def __init__(self, item, next):
self.item = item
self.next = next
class Stack:
def __init__(self):
self.top = None
def push(self, value):
self.top = Node(value, self.top)
def pop(self):
if self.top is None:
return None
topNode = self.top
self.top = self.top.next
return topNode.item
def is_empty(self):
return self.top is None
class Node:
def __init__(self, item, next):
self.item = item
self.next = next
class Queue:
def __init__(self):
self.front = None
def push(self, value):
if not self.front:
self.front = Node(value, None)
return
node = self.front
while node and node.next:
node = node.next
node.next = Node(value, None)
def pop(self):
if not self.front:
return None
node = self.front
self.front = self.front.next
return node.item
def is_empty(self):
return self.front is None
import collections
class MyHashMap:
def __init__(self):
self.size = 1000
self.table = collections.defaultdict(ListNode)
def put(self, key: int, value: int) -> None:
index = key % self.size
# 인덱스에 노드가 없다면 삽입 후 종료
if self.table[index].value is None:
self.table[index] = ListNode(key, value)
return
# 인덱스에 노드가 존재하는 경우 연결 리스트 처리
p = self.table[index]
while p:
if p.key == key:
p.value = value
return
if p.next is None:
break
p = p.next
p.next = ListNode(key, value)
def get(self, key: int) -> int:
index = key % self.size
if self.table[index].value is None:
return -1
# 노드가 존재할 때 일치하는 키 탐색
p = self.table[index]
while p:
if p.key == key:
return p.value
p = p.next
return -1
def remove(self, key: int) -> None:
index = key % self.size
if self.table[index].value is None:
return
p = self.table[index]
if p.key == key:
self.table[index] = ListNode() if p.next is None else p.next
return
prev = p
while p:
if p.key == key:
prev.next = p.next
return
prev, p = p, p.next
class ListNode:
def __init__(self, key=None, value=None):
self.key = key
self.value = value
self.next = None
# 재귀 구조
def recursive_dfs(v, discovered = []):
discovered.append(v)
for w in graph[v]:
if w not in discovered:
discovered = recursive_dfs(w, discovered)
return discovered
# 스택 이용 반복 구조
def iterative_dfs(start_v):
discovered = []
stack = [start_v]
while stack:
v = stack.pop()
if v not in discovered:
discovered.append(v)
for w in graph[v]:
stack.append(w)
return discovered
def bfs_queue(start):
visited = [start]
q = deque([start])
while q:
node = q.popleft()
for adj in graph[node]:
if adj not in visited:
q.append(adj)
visited.append(adj)
return visited