239. 滑动窗口最大值&347.前 K 个高频元素

239. 滑动窗口最大值

from collections import deque

class MyQueue:
    def __init__(self):
        self.que = deque()
    def pop(self,value):
        if self.que and value == self.que[0]:
            self.que.popleft()
    def push(self,value):
        while self.que and value>self.que[-1]:
            self.que.pop()
        self.que.append(value)
    def front(self):
        return self.que[0]
class Solution:
    def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
        que = MyQueue()
        result = []
        for i in range(k):  ###先开始初始化值 
            que.push(nums[i])
        result.append(que.front())
        for i in range(k,len(nums)):
            que.pop(nums[i-k])
            que.push(nums[i])
            result.append(que.front())
        return result

            

先构造单调队列再从总体思路出发

347.前 K 个高频元素

import heapq
class Solution:
    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
        map1 = {}
        for i in range(len(nums)):
            map1[nums[i]] = map1.get(nums[i],0)+1
        pri_heapq = []
        for value,freq in map1.items():
            heapq.heappush(pri_heapq,(freq,value))
            if len(pri_heapq)>k:
                heapq.heappop(pri_heapq)
        result = [0]*k
        for i in range(k-1,-1,-1):
            result[i] = heapq.heappop(pri_heapq)[1] ###错误在这里
        return result

构造小顶栈因为pop的是队列中最小值，所以要倒叙赋值才是从从大到小的结果