索引
- 最小栈
- 全O1结构
- LRU
题解
- 最小栈
class MinStack:
def __init__(self):
"""
initialize your data structure here.
"""
self.stack = list()
self.t_stack = list()
def push(self, x: int) -> None:
if len(self.stack) > 0 and x <= self.t_stack[-1]:
self.t_stack.append(x)
if len(self.stack) ==0:
self.t_stack.append(x)
self.stack.append(x)
def pop(self) -> None:
if len(self.stack) == 0:
return None
val = self.stack[-1]
self.stack = self.stack[:-1]
if val == self.t_stack[-1]:
self.t_stack = self.t_stack[:-1]
return val
def top(self) -> int:
if len(self.stack) == 0:
return None
return self.stack[-1]
def getMin(self) -> int:
if len(self.stack) == 0:
return None
return self.t_stack[-1]
- 全O1结构
class AllOne:
def __init__(self):
"""
Initialize your data structure here.
"""
self.map = dict()
self.counts = list()
def inc(self, key: str) -> None:
"""
Inserts a new key <Key> with value 1. Or increments an existing key by 1.
"""
if key not in self.map:
self.counts.append((key,1))
self.map[key] = len(self.counts) - 1
return
idx = self.map[key]
old_count = self.counts[idx][1]
swap_idx = idx
for i in range(idx,-1,-1):
item = self.counts[i]
c = item[1]
if c >= old_count + 1:
break
else:
swap_idx = i
if swap_idx != idx:
item = self.counts[swap_idx]
k = item[0]
self.map[k] = idx
self.counts[swap_idx],self.counts[idx] = self.counts[idx],self.counts[swap_idx]
idx = swap_idx
self.counts[idx] = (key,old_count + 1)
self.map[key] = idx
def dec(self, key: str) -> None:
"""
Decrements an existing key by 1. If Key's value is 1, remove it from the data structure.
"""
if key not in self.map:
return
idx = self.map[key]
old_count = self.counts[idx][1]
swap_idx = idx
for i in range(idx,len(self.counts)):
item = self.counts[i]
c = item[1]
if c<= old_count - 1:
break
else:
swap_idx = i
if swap_idx != idx:
item = self.counts[swap_idx]
k = item[0]
self.map[k] = idx
self.counts[swap_idx], self.counts[idx] = self.counts[idx], self.counts[swap_idx]
idx = swap_idx
if old_count -1 ==0:
self.counts = self.counts[:-1]
del(self.map[key])
else:
self.counts[idx] = (key, old_count -1)
self.map[key] = idx
def getMaxKey(self) -> str:
"""
Returns one of the keys with maximal value.
"""
if len(self.counts) == 0:
return ''
m = self.counts[0]
return m[0]
def getMinKey(self) -> str:
"""
Returns one of the keys with Minimal value.
"""
if len(self.counts) == 0:
return ''
m = self.counts[-1]
return m[0]
- LRU
class LRUCache:
def __init__(self, capacity: int):
self.stack = list()
self.map = dict()
self.cap = capacity
def get(self, key: int) -> int:
if key not in self.map:
return -1
idx = self.map[key]
for i in range(idx+1, len(self.stack)):
val = self.stack[i]
k,v = val[0], val[1]
self.map[k] -= 1
top = self.stack[idx]
self.stack[idx:-1] = self.stack[idx+1:]
self.stack[-1] = top
k,v = top[0],top[1]
self.map[k] = len(self.stack) -1
return v
def put(self, key: int, value: int) -> None:
if len(self.stack) <self.cap:
if key not in self.map:
self.stack.append((key,value))
self.map[key] = len(self.stack) - 1
else:
idx = self.map[key]
self.stack[idx] = (key,value)
return
if key not in self.map:
bottom = self.stack[0]
k = bottom[0]
del(self.map[k])
for k in self.map:
self.map[k] -= 1
self.stack[0:-1] = self.stack[1:]
self.stack[-1] = (key,value)
self.map[key] = len(self.stack) - 1
else:
idx = self.map[key]
for i in range(idx+1,len(self.stack)):
val = self.stack[i]
k,v = val[0],val[1]
self.map[k] -=1
self.stack[idx:-1] = self.stack[idx+1:]
self.stack[-1] = (key,value)
self.map[key] = len(self.stack) - 1
来源：oschina
链接：https://my.oschina.net/u/4215839/blog/3224574