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Python Articles
Page 832 of 855
Power of Three in Python
Suppose we have a number n. We have to check whether the number is the power of 3 or not. So if the number is like n = 27, that is the power of 3, the result will be true, if n = 15, it will be false.To solve this, we will follow these steps −We will use the Logarithm to solve thisif [log10(n) / log10(3)] mod 1 == 0, then it will be power of three, otherwise notExampleLet us see the following implementation to get a better understanding −class Solution(object): def isPowerOfThree(self, n): """ :type n: int :rtype: bool """ if not n or n
Read MoreFirst Unique Character in a String in Python
Suppose we have a string and we have to find the first unique character in the string. So if the string is like “people”, the first letter whose occurrence is one is ‘o’. So the index will be returned, that is 2 here. If there is no such character, then return -1.To solve this, we will follow these steps −create one frequency mapfor each character c in the string, doif c is not in frequency, then insert it into frequency, and put value 1otherwise, increase the count in frequencyScan the frequency map, if the value of a specific key is ...
Read MoreCount Primes in Python
Suppose we have a limit n. We have to count the number of primes present in the range 2 to n. So if n = 10, the result will be 4. As there are four primes before 10, they are 2, 3, 5, 7.To solve this, we will follow this approach −count = 0take one array prime = of size n + 1, and fill it with Falsefor i = 0 to n, doif prime[i] = false, thenincrease count by 1set j = 2while j * i
Read MoreRotate String in Python
Suppose we have two strings, A and B. We will rotate the string A and check whether it matches with B at any position of rotating, if so then return true, otherwise false. For example, if A = 'abcde', and B = 'bcdea' So answer will be true, as A can be converted to B after rotating it.To solve this, we will follow these steps −When both A and B are empty, then return true, when both are of different length then return falseA := concatenate A after Ai := 0, and j := 0while i < length of Aif ...
Read MoreRemove Duplicates from Sorted Array in Python
Suppose we have a sorted list A. We have to return the length of the array after removing all duplicate entries. We have to perform this in O(1) extra space. So we have to do the operation in-place.For an example, suppose A = [1, 1, 2, 2, 2, 3, 3, 3, 3, 4, 5, 5, 5, 6] Then the output will be 6, as there are six distinct elements.To solve this, follow these steps −If the list is empty, return 0otherwise, initially take prev = first element of A. And define length = 0for i := 1 to n-1, doif ...
Read MoreNumber of operations required to make all array elements Equal in Python
We have given an array of elements, and we have to make them all equal by incrementing the elements by 1. We are allowed to increment n - 1 element at each step. Our goal is to calculate the total number of operations required to make all the array elements equal.For example, if you take the list [1, 2, 3], it took three operations to make all the elements equal. One solution to the problem is. Find the most significant number at each step and increment the rest of the elements by 1. Let's write the code.Exampledef main(): # ...
Read MoreReverse Vowels of a String in Python
Suppose we have a lowercase string. Our task is to reverse the vowels present in the string. So if the string is “hello”, then the string after vowel reversal will be “holle”. For string “programming”, it will be “prigrammong”To solve this, we will follow these steps −Take the string and make a list of vowels, and store their indices as wellreverse the vowel listset idx := 0for i := 0 to length of given string – 1if i is in index list −put vowels[i] into final stringidx := idx + 1otherwise put string[i] into final stringreturn the list as a ...
Read MoreReverse Only Letters in Python
Suppose we have a string S, we have to find the reversed string where all characters that are not a letter will not change their positions and all letters reverse their positions. So if the given string is "a-bC-dEf-ghIj", then output will be "j-Ih-gfE-dCba"To solve this, we will follow these steps −We will use the regular expression library to solve thisif S is empty, then return Sstr := an empty string, index1 := 0 and index2 := length of S – 1while index1 < length of Sif index2 >= 0 and S[index1] is alphabet and S[index2] is alphabetstr := str ...
Read MoreRemove All Adjacent Duplicates In String in Python
Suppose we have a string S of lowercase letters; a duplicate removal operation will be performed. This will be done by choosing two adjacent and equal letters, and removing them.We will repeatedly remove duplicates from S until no duplicates are remaining.Return the string after all such duplicate removals have been completed. It is guaranteed that the answer is unique.Suppose the string is “abbacaca”, then answer will be “caca”. At first delete duplicates bb, then string is “aacaca”, then remove aa, then string is “caca”, then no such duplicates are there.To solve this, we will follow these steps −Define an array ...
Read MoreNested list comprehension in python
A nested list is a list within a list. Python provides features to handle nested list gracefully and apply common functions to manipulate the nested lists. In this article we will see how to use list comprehension to create and use nested lists in python.Creating a MatrixCreating a matrix involves creating series of rows and columns. We can use for loop for creating the matrix rows and columns by putting one python list with for loop inside another python list with for loop.Examplematrix = [[m for m in range(4)] for n in range(3)] print(matrix)Running the above code gives us the ...
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