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Leetcode datastructures

1. Python
   (1) Dict:

a={}
a['x'] = 123
a.pop('x')
a.get('x',0)
del a['x']
a.items()

(2) set

a=set()
a=set([1,2,3])
a.add('x')
a.remove('x')

(3) collections.defaultdict

import collections.defaultdict as defaultdict
a=defaultdict(list)
a['x'].append(1)

(4)collections.deque:

a=deque()
a.append(1)
a.pop()
a.appendleft(1)
a.popleft()

(5) heapq

q=heapq.heapify(list)
heapq.heappush(q,1)
heapq.heappop(q)
q[0] # smallest, min-heap by default
heapq.nlargest(k,q) # q doesn't need to be heap
heapq.nsmallest(k,q) # q doesn't need to heap

(6) collections.Counter

a=Counter([1,1,2,2,2,3])
a[1]
a[1]+=1
a.update([1,1,2])
del a[1]

(7) list

a=[1,2,3]
a.append()
a.pop()
a.copy()

(8) @lru_cache(None)

(9) sorted(iterable, key, reverse=False) # ascending

2. C++
   (1) vector

vector<int> a;
a.begin() //iterator
a.end() 
a.size()
a.empty()
a[0]
a.at(0)
a.front()
a.back()
a.push_back(1)
a.pop_back()
a.erase(index)
a.clear()

(2) deque

deque<int> a;
a.begin() //iterator
a.end() 

a[0]
a.at(0)
a.front()
a.back()

a.push_front(1)
a.push_back(1)
a.pop_fron()
a.pop_back()

(3) dict
unordered_map is hash table, but map is a balanced search tree which is sorted and search is O(log(N))

在这里插入代码片

https://leetcode.com/discuss/study-guide/1154632/c-stl-powerful-guide-compiled-list-of-popular-stl-operations