Kutengeneza muundo wa kaida ina maana kuchanganya miundo iliyopo ili kila operesheni inayohitajika ikafikia utata wake wa lengo, na muundo mmoja unakula dhaifu ya mwingine. Mbinu ya kawaida ni kuunganisha ramani ya hash na array, heap, au orodha iliyounganishwa.
Mahitaji: , na kila mmoja katika O(1). Ramani ya hash pekee haiwezi kufanya O(1) nasibu; array pekee haiwezi kufanya O(1) kuondolewa. .
insert(x)remove(x)getRandom()import random
class RandomizedSet:
def __init__(self):
self.idx = {} # value -> index in list
self.vals = [] # values for O(1) random pick
def insert(self, x): # O(1)
if x in self.idx: return False
self.idx[x] = len(self.vals)
self.vals.append(x)
return True
def remove(self, x): # O(1): swap with last, pop
if x not in self.idx: return False
i, last = self.idx[x], self.vals[-1]
self.vals[i] = last # move last into the hole
self.idx[last] = i
self.vals.pop()
del self.idx[x]
return True
def getRandom(self): # O(1)
return random.choice(self.vals)
1. List every required operation + its target complexity.
2. For each, name a structure that hits it:
by key O(1) -> hash map
by index O(1) -> array
min/max O(log n) -> heap
ordered O(log n) -> balanced tree / skip list
O(1) splice -> doubly linked list
3. COMBINE them; use the hash map to map keys -> positions/nodes
in the other structure so updates stay O(1).
4. Verify each operation against its target.
| Mtindo | Miundo iliyochanganywa | Inaruhusu |
|---|---|---|
| LRU cache | ramani ya hash + orodha iliyounganishwa kwa njia mbili | O(1) get/put |
| Seti inayonasibu O(1) | ramani ya hash + array | O(1) insert/remove/random |
| Min katika O(1) juu ya stack | stack + min-stack ya msaada | O(1) getMin |
Sistemi halisi nadra inahitaji muundo mmoja wa kitabu — inahitaji muundo wa composite unaounganishwa na mtindo maalum wa kufikia, ambayo ni nini hasa miundo hii inatoa.
Wajumbe wa mahojiano hutumia matatizo haya kujaribu kama unaweza kufikiria kutoka gharama za operesheni hadi muundo wa composite, ujuzi muhimu nyuma ya muundo wa mfumo wenye utendaji wa juu.