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https://github.com/TheAlgorithms/Python.git
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Added Dequeue in Python
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97arushisharma
28
data_structures/Binary Tree/FenwickTree.py
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28
data_structures/Binary Tree/FenwickTree.py
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class FenwickTree:
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def __init__(self, SIZE): # create fenwick tree with size SIZE
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self.Size = SIZE
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self.ft = [0 for i in range (0,SIZE)]
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def update(self, i, val): # update data (adding) in index i in O(lg N)
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while (i < self.Size):
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self.ft[i] += val
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i += i & (-i)
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def query(self, i): # query cumulative data from index 0 to i in O(lg N)
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ret = 0
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while (i > 0):
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ret += self.ft[i]
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i -= i & (-i)
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return ret
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if __name__ == '__main__':
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f = FenwickTree(100)
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f.update(1,20)
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f.update(4,4)
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print (f.query(1))
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print (f.query(3))
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print (f.query(4))
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f.update(2,-5)
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print (f.query(1))
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print (f.query(3))
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90
data_structures/Binary Tree/LazySegmentTree.py
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90
data_structures/Binary Tree/LazySegmentTree.py
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import math
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class SegmentTree:
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def __init__(self, N):
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self.N = N
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self.st = [0 for i in range(0,4*N)] # approximate the overall size of segment tree with array N
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self.lazy = [0 for i in range(0,4*N)] # create array to store lazy update
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self.flag = [0 for i in range(0,4*N)] # flag for lazy update
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def left(self, idx):
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return idx*2
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def right(self, idx):
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return idx*2 + 1
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def build(self, idx, l, r, A):
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if l==r:
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self.st[idx] = A[l-1]
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else :
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mid = (l+r)//2
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self.build(self.left(idx),l,mid, A)
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self.build(self.right(idx),mid+1,r, A)
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self.st[idx] = max(self.st[self.left(idx)] , self.st[self.right(idx)])
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# update with O(lg N) (Normal segment tree without lazy update will take O(Nlg N) for each update)
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def update(self, idx, l, r, a, b, val): # update(1, 1, N, a, b, v) for update val v to [a,b]
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if self.flag[idx] == True:
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self.st[idx] = self.lazy[idx]
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self.flag[idx] = False
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if l!=r:
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self.lazy[self.left(idx)] = self.lazy[idx]
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self.lazy[self.right(idx)] = self.lazy[idx]
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self.flag[self.left(idx)] = True
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self.flag[self.right(idx)] = True
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if r < a or l > b:
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return True
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if l >= a and r <= b :
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self.st[idx] = val
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if l!=r:
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self.lazy[self.left(idx)] = val
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self.lazy[self.right(idx)] = val
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self.flag[self.left(idx)] = True
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self.flag[self.right(idx)] = True
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return True
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mid = (l+r)//2
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self.update(self.left(idx),l,mid,a,b,val)
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self.update(self.right(idx),mid+1,r,a,b,val)
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self.st[idx] = max(self.st[self.left(idx)] , self.st[self.right(idx)])
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return True
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# query with O(lg N)
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def query(self, idx, l, r, a, b): #query(1, 1, N, a, b) for query max of [a,b]
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if self.flag[idx] == True:
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self.st[idx] = self.lazy[idx]
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self.flag[idx] = False
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if l != r:
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self.lazy[self.left(idx)] = self.lazy[idx]
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self.lazy[self.right(idx)] = self.lazy[idx]
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self.flag[self.left(idx)] = True
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self.flag[self.right(idx)] = True
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if r < a or l > b:
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return -math.inf
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if l >= a and r <= b:
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return self.st[idx]
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mid = (l+r)//2
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q1 = self.query(self.left(idx),l,mid,a,b)
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q2 = self.query(self.right(idx),mid+1,r,a,b)
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return max(q1,q2)
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def showData(self):
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showList = []
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for i in range(1,N+1):
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showList += [self.query(1, 1, self.N, i, i)]
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print (showList)
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if __name__ == '__main__':
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A = [1,2,-4,7,3,-5,6,11,-20,9,14,15,5,2,-8]
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N = 15
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segt = SegmentTree(N)
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segt.build(1,1,N,A)
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print (segt.query(1,1,N,4,6))
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print (segt.query(1,1,N,7,11))
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print (segt.query(1,1,N,7,12))
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segt.update(1,1,N,1,3,111)
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print (segt.query(1,1,N,1,15))
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segt.update(1,1,N,7,8,235)
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segt.showData()
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64
data_structures/Binary Tree/SegmentTree.py
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64
data_structures/Binary Tree/SegmentTree.py
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import math
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class SegmentTree:
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def __init__(self, N):
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self.N = N
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self.st = [0 for i in range(0,4*N)] # approximate the overall size of segment tree with array N
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def left(self, idx):
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return idx*2
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def right(self, idx):
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return idx*2 + 1
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def build(self, idx, l, r, A):
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if l==r:
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self.st[idx] = A[l-1]
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else :
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mid = (l+r)//2
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self.build(self.left(idx),l,mid, A)
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self.build(self.right(idx),mid+1,r, A)
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self.st[idx] = max(self.st[self.left(idx)] , self.st[self.right(idx)])
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def update(self, idx, l, r, a, b, val): # update(1, 1, N, a, b, v) for update val v to [a,b]
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if r < a or l > b:
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return True
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if l == r :
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self.st[idx] = val
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return True
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mid = (l+r)//2
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self.update(self.left(idx),l,mid,a,b,val)
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self.update(self.right(idx),mid+1,r,a,b,val)
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self.st[idx] = max(self.st[self.left(idx)] , self.st[self.right(idx)])
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return True
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def query(self, idx, l, r, a, b): #query(1, 1, N, a, b) for query max of [a,b]
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if r < a or l > b:
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return -math.inf
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if l >= a and r <= b:
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return self.st[idx]
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mid = (l+r)//2
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q1 = self.query(self.left(idx),l,mid,a,b)
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q2 = self.query(self.right(idx),mid+1,r,a,b)
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return max(q1,q2)
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def showData(self):
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showList = []
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for i in range(1,N+1):
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showList += [self.query(1, 1, self.N, i, i)]
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print (showList)
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if __name__ == '__main__':
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A = [1,2,-4,7,3,-5,6,11,-20,9,14,15,5,2,-8]
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N = 15
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segt = SegmentTree(N)
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segt.build(1,1,N,A)
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print (segt.query(1,1,N,4,6))
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print (segt.query(1,1,N,7,11))
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print (segt.query(1,1,N,7,12))
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segt.update(1,1,N,1,3,111)
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print (segt.query(1,1,N,1,15))
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segt.update(1,1,N,7,8,235)
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segt.showData()
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103
data_structures/Binary Tree/binary_seach_tree.py
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103
data_structures/Binary Tree/binary_seach_tree.py
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'''
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A binary search Tree
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'''
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class Node:
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def __init__(self, label):
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self.label = label
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self.left = None
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self.right = None
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def getLabel(self):
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return self.label
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def setLabel(self, label):
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self.label = label
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def getLeft(self):
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return self.left
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def setLeft(self, left):
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self.left = left
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def getRight(self):
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return self.right
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def setRight(self, right):
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self.right = right
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class BinarySearchTree:
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def __init__(self):
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self.root = None
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def insert(self, label):
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# Create a new Node
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node = Node(label)
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if self.empty():
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self.root = node
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else:
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dad_node = None
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curr_node = self.root
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while True:
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if curr_node is not None:
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dad_node = curr_node
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if node.getLabel() < curr_node.getLabel():
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curr_node = curr_node.getLeft()
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else:
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curr_node = curr_node.getRight()
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else:
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if node.getLabel() < dad_node.getLabel():
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dad_node.setLeft(node)
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else:
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dad_node.setRight(node)
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break
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def empty(self):
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if self.root is None:
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return True
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return False
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def preShow(self, curr_node):
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if curr_node is not None:
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print(curr_node.getLabel(), end=" ")
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self.preShow(curr_node.getLeft())
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self.preShow(curr_node.getRight())
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def getRoot(self):
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return self.root
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'''
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Example
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8
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/ \
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3 10
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/ \ \
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1 6 14
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/ \ /
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4 7 13
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'''
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t = BinarySearchTree()
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t.insert(8)
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t.insert(3)
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t.insert(1)
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t.insert(6)
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t.insert(4)
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t.insert(7)
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t.insert(10)
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t.insert(14)
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t.insert(13)
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t.preShow(t.getRoot())
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