arrays vs lists, binary search

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[muralidhar]

arrays - uniform time to access any random element, however inserting/removing takes a lotta time because the constraint that array elements should be contiguous, hence shifting op needs to be performed. linked lists eliminate the need of shifting, but increase time complexity of accessing elements. swapping elements in array is lesser time than lists

[arjunpukale]

The binary search program is not working
The mid condition must be checked first then empty condition then it works properly

[abhinavtyagi]

At 17:50, what if we don't write return in the last two conditions and only call the function bsearch(seq, v, l, mid) ??

[muralidhar]

python lists are best of both the arrays and linked lists, in it they take constant time for accessing any element like arrays, but also they allow for efficient addition/removal of elements like linked lists.

[weirdo-beardo]

At 17:40

Shouldn't we use elif instead of only if, to recursively search in RHS part of the sequence?

[Jaimin_Bariya]

Jp here again [comment number 25]

Thank you, Sir, :)

[adeelshafi]

what is r & l in function parameters? like when we call that function in promt window of python what value we pass through in terms of r & l?

[akshaypatil]

With the Binary search program it won't check the last place.
For eg if it is a list with 7 elements, last index being 6, due to (l-r)==0 condition, 6th index won't be checked even if it has the desire value (v).

this is will help
def BinarySearchWithRange(seq, v, l, r):
mid = (l+r)//2
if (r-l) ==0 and seq[mid] == v:
return(True)
if (r-l) ==0 and seq[mid] != v:
return(False)
if (seq[mid] == v):
return(True)
elif seq[mid] > v:
return(BinarySearchWithRange(seq, v, l, mid))
else:
return(BinarySearchWithRange(seq, v, mid+1, r))

[kaunajbanerjee]

In the "Lists vs Arrays" discussion, the lists being studied are not Python's lists, but what is commonly referred to as linked lists.


The built-in data structure List in Python may be treated as conventional arrays (mentioned at the end). According to the Python docs, accessing an element from a list is O(1) and inserting is O(n).


The link below provides a table of the time complexities of all list operations for those interested.

[sumedh]

Q: Previous program (findpos, where we found the position), we used "Break", cant we use "Return" instead of "Break" there... Pls do rply !

[akhilantony]

how can t(1) takes only one step? pls reply

[chakradharkasturi]

According to python design documentation Python lists are variable length arrays.

[bejorrani]

def Binary(sqn, v):
sqn.sort()
start=0
end=len(sqn)-1
while start<end:
mid=(start+end)//2
if end-start==1 :
if sqn[mid]==v or sqn[mid+1]==v:
return True
else:
return False
if v==sqn[mid]:
return True
elif v>sqn[mid]:
start=mid+1
else:
end=mid
returnFalse

Fucking bastard, what a shame on IIT, worst teaching ever .