[python]ハッシュテーブル(2)

に質問重複文字のない最長部分文字列

プール(スライドウィンドウとダブルポインタで寸法を調整)

def lengthOfLongestSubstring(self,s):
    used={}
    max_length , start = 0,0
    for index, char in enumerate(s):
        # 이미 등장했던 문자라면 'start' 위치 갱신
        if char in used and start <= used[char]:
            start = used[char] + 1
        else:
            max_length = max(max_length, index - start + 1)
        
        #현재 문자의 위치 삽입
        used[char] = index
        
    return max_length 
        

に質問親K周波数要素

草。カウンタを使用して負の値の順に抽出

import heapq
import collections
def topKFrequent( nums,k):
    freqs = collections.Counter(nums)
    freqs_heap = []
    # 힙에 음수로 삽입
    for f in freqs:
        heapq.heappush(freqs_heap , (-freqs[f],f))
    
    topk = list()
    #k번 만큼 추출, 최소 힙이므로 가장 작은 음수 순으로 추출
    
    for _ in range(k):
        topk.append(heapq.heappop(freqs_heap)[1])
        
    return topk

Python Down方式

def topKFrequent(nums,k):
    return list(zip(*collections.Counter(nums).most_common(k)))[0]

fruits = ['lemon' , 'pear' ,'watermelon']
for f in fruits:
    print(f, end=' ')

print(*fruits)