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Completed Design1 #2630

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39 changes: 39 additions & 0 deletions HashSet.py
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Original file line number Diff line number Diff line change
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# Time Complexity : O(1)
# Space Complexity : O(n)
# Did this code successfully run on Leetcode : Yes
# Any problem you faced while coding this : No
# Approach : two level bucket structure (primary -> secondary) with boolean arrays for constant time access.

class MyHashSet:
def __init__(self):
self.primaryBucketSize = 1000
self.secondaryBucketSize = 1001 # for division edge case
self.storage = [[] for _ in range(self.primaryBucketSize)]

def getPrimaryHash(self, key: int) -> int:
return key % self.primaryBucketSize

def getSecondaryHash(self, key: int) -> int:
return key // self.secondaryBucketSize

def add(self, key: int) -> None:
primaryHash = self.getPrimaryHash(key)
if self.storage[primaryHash] == []:
self.storage[primaryHash] = [False] * (self.secondaryBucketSize)

secondaryHash = self.getSecondaryHash(key)
self.storage[primaryHash][secondaryHash] = True

def remove(self, key: int) -> None:
primaryHash = self.getPrimaryHash(key)
if not self.storage[primaryHash]:
return
secondaryHash = self.getSecondaryHash(key)
self.storage[primaryHash][secondaryHash] = False

def contains(self, key: int) -> bool:
primaryHash = self.getPrimaryHash(key)
if not self.storage[primaryHash]:
return False
secondaryHash = self.getSecondaryHash(key)
return self.storage[primaryHash][secondaryHash]
28 changes: 28 additions & 0 deletions MinStack.py
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# Time Complexity : O(1)
# Space Complexity : O(n)
# Did this code successfully run on Leetcode : Yes
# Any problem you faced while coding this : No
# Approach : Only when a new min appears, we store the previous min in the stack,
# so that when the current min is removed, we can restore the old one in constant time.

class MinStack:

def __init__(self):
self.stack = []
self.min = float('inf')

def push(self, val: int) -> None:
if val <= self.min:
self.stack.append(self.min)
self.min = val
self.stack.append(val)

def pop(self) -> None:
if self.min == self.stack.pop():
self.min = self.stack.pop()

def top(self) -> int:
return self.stack[-1]

def getMin(self) -> int:
return self.min