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Page 1566 of 2109
Count permutations possible by replacing ‘?’ characters in a Binary String
In this problem, we have given a string containing 0, 1, and ? characters. We need to find permutations of the string by replacing ‘?’ with 0 and 1. The logic to solve the problem is that we can replace every ‘?’ with either 0 or 1. So, by replacing one ‘?’, we can generate two different permutations, and by replacing N ‘?’ with 2 possibilities, we can generate 2^N permutations. In this tutorial, we will learn two different approaches to solving the given problem. Problem statement – We have given string str containing ‘0’, ‘1’ and ‘?’ characters. We ...
Read MoreCount new pairs of strings that can be obtained by swapping first characters of pairs of strings from given array
In this problem, we need to select the pair of strings and swap their first character. After that, we need to count the total number of new pairs. We can solve the problem by swapping the first character of each pair and checking whether it exists in the array. The efficient approach to solve the problem can be using the hashmap data structure. Problem statement – We have given an array containing N strings. We can take any of two strings from all array elements and swap the first characters of both strings. We need to count the total ...
Read MoreCheck if the number formed by concatenating all array elements is a Harshad number or not
In this problem, we have given the array of integers. We need to combine all elements in a single integer and check if it is a Harshad number. Before we move with the solution, let’s understand Harshad number. All numbers are Harshad numbers which are divisible by the sum of their digits. For example, 12 is Harshad number, as 12 is divisible by 3 = 1 + 2. To solve the problem, we can combine all array elements, and after that, we can check whether the resultant number is the Harshad number. Problem statement – We have given an array ...
Read MoreCheck if all characters of a string can be made equal by increments or decrements
In this problem, we need to check if we can make all characters of strings equal by increment and decrement operations. We can get the weight of each character based on their ASCII values and check whether the total weight can be used to make all characters equal. Problem statement – We have given string str of length N containing lowercase alphabetical characters. We need to check whether we can make all characters of the string equal by choosing any of two characters, increasing one, and decreasing another by 1. If possible, print ‘yes’, else ‘no’. Sample examples Input– ...
Read MoreRemoving Odd Elements From List in Python
In Python, lists are a versatile data structure that allows you to store and manipulate collections of items. There may be use cases where you need to remove specific elements from a list based on certain criteria. In this tutorial, we will learn how to remove odd elements from a list in Python. Using a For Loop and remove() method The approach is to use a for loop to iterate through each element of the list and check if the element is odd or even and then use the remove() method to remove it from the list. Syntax remove() remove(item) ...
Read MoreConvert a NumPy array to an image
The array created using the Numpy library can be converted into an image using the PIL or opencv libraries in python programming language. Let’s see about each library one by one. Python Image Library PIL is abbreviated as Python Image Library, which is an image processing libraries in python. It is a light weight and easy to use library to perform the image processing tasks like reading, writing, resizing and cropping the images. This library performs all the basic image processing tasks but don’t have any advanced features required for computer vision applications. We have a function in ...
Read MoreConvert a NumPy array into a csv file
The Numpy is the library in the python programming language which is abbreviated as Numerical Python. It is used to do the mathematical, scientific and statistical calculations within less time. The output of the numpy functions will be an array. An array created by the numpy functions can be stored in the CSV file using a function namely, savetxt(). Numpy array into a .csv file CSV is abbreviated as Comma Separated Values. This is the file format most widely used in the Data Science. This stores the data in a tabular format where the column holds the data fields and ...
Read MoreCompute the mean, standard deviation, and variance of a given NumPy array
Mean, Standard Deviation and Variance are the statistical measures which are used to describe the distribution of the given dataset data. In Numpy library, we have the functions to calculate the mean, standard deviation and variance of the arrays. Let’s see one by one in detail. Mean Mean is also known as average, which is the sum of all the elements in the array divided by the total number of elements. It is used to represent the central tendency of the data. Syntax Following is the syntax for applying the mean function on the arrays - numpy.mean(arr) ...
Read MoreCompute the inverse of a matrix using inv() function of NumPy
The inverse matrix is a matrix that gives a multiplicative identity when multiplied with its original matrix. It is denoted by A-1. The inverse matrix can be calculated for the square matrices with the n x n size. The mathematical formula given for calculating the inverse matrix is as follows. A-1 . A = A . A-1 = I Where, A is the original matrix. A-1 is the inverse of the original matrix A. I is the identity matrix. Let’s take the original matrix as A with the size 2 x 2 and elements as ...
Read MoreCompute the covariance matrix of two given NumPy arrays
Covariance is the measure of two variables that defines how they are related to each other. In other words, it measures the extent to which one variable is associated with the changes in the other variable. When the covariance of the variables is positive, it implies that both variables are moving in the same direction i.e. if one variable tends to increase, as a result, the value of the other variable also increases. When the covariance of the variables is negative then it represents the two variables are moving in opposite direction i.e. if one variable increases the value ...
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