Python Articles - Page 689 of 829

Suppose we have a string S of '(' and ')' parentheses, we add the minimum number of parentheses at any positions, so that the resulting parentheses string is valid. A parentheses string is valid if and only if −It is the empty stringIt can be written as XY (X concatenated with Y), where X and Y are valid stringsIt can be written as (A), where A is a valid string.So if the string is like "()))((", then we need to add 4 more parentheses to make the string valid.To solve this, we will follow these steps −if S is empty, ... Read More

Suppose we have a list of words and a pattern, and we have to find which words in words matches the pattern. Here a word matches the pattern if there exists a permutation of letters p so that after replacing every letter x in the pattern with p(x), we get the target word. We have to find a list of the words in words that match the given pattern.So for example, if the input is like ["abc", "deq", "mee", "aqq", "dkd", "ccc"] and pattern is “abb”, then the output will be [“mee”, “aqq”], here mee and aqq are matching the ... Read More

Suppose we have two traversal sequences Preorder and Postorder, we have to generate the binary tree from these two sequences. So if the sequences are [1, 2, 4, 5, 3, 6, 7], [4, 5, 2, 6, 7, 3, 1], then the output will beTo solve this, we will follow these steps −ans := make a tree node by taking value pre[0], stack := empty stack, and insert ansi := 1 and j := 0while i < length of pre and j < length of postif stack top value = post[j], then increase j by 1, pop from stack, and go ... Read More

Suppose one encoded string S is given. We have to find and write the decoded string to a tape, here the encoded string is read one character at a time and the following steps are performed −If the character read is a letter, that letter is simply written onto the tape.If the character read is a digit, the entire current tape is repeatedly written digit – 1 more times in total.Now if some encoded string S, and an index K is given, find and return the K-th letter (starting indices from 1) in the decoded string.So if the string is ... Read More

Suppose we have a n x n matrix where each of the rows and columns are sorted in increasing order, we have to find the kth smallest element in the matrix. Note that it is the kth smallest element in the sorted order, not the kth unique element. So if the input is like [[1, 5, 9], [10, 11, 13], [12, 13, 15]], if k = 8, then the output will be 13.To solve this, we will follow these steps −define one method called checkVal() and the arguments are matrix and valuei := 0, j := length of matrix[0] – ... Read More

Suppose we have a 2D board containing X and O. Capture all regions surrounded by X. A region is captured by changing all Os into Xs in that surrounded region.XXXXXOOXXXOXXOXXAfter running the output will beXXXXXXXXXXXXXOXXTo solve this, we will follow these steps −If board is not present, then return blank boardfor i in range 0 to number of rows – 1 −if board[i, 0] = ‘O’, then make_one(board, i, 0)if board[i, length of row - 1] = ‘O’, then make_one(board, i, length of row – 1)for i in range 0 to number of cols – 1 −if board[0, i] = ... Read More

Suppose we have a m x n matrix filled with non-negative integers, find a path from top left corner to bottom right corner which minimizes the sum of all numbers along its path. Movements can only be either down or right at any point in time. So for example, if the matrix is like below131151421The output will be 7, the path will be 1, 3, 1, 1, 1, this will minimize the sumLet us see the steps −a := number of rows, b := number of columnsi := a – 1, j := b – 1while j >= 0matrix[a, j] ... Read More

In this tutorial, we are going to learn how to calculate Wind Chill Index in Python. We have the formula to calculate the WCI and it's straightforward. We are going to use the following formula to calculate the WCI.Twc(WCI) = 13.12 + 0.6215Ta – 11.37v+0.16 + 0.3965Tav+0.16whereTwc = Wind Chill Index (Based on Celsius temperature scale)Ta = Air Temperature (in degree Celsius)v = Wind Speed (in miles per hour)We are going to use the math module function wherever we need them. Using the math module function decreases the execution time of a program.Follow the below steps to complete the program.Import the math moduleInitialize the ... Read More

In this tutorial, we are going to write an anonymous function using lambda to rearrange positive and negative number in a list. We need the pick the negative numbers and then positive numbers from a list to create a new one.AlgorithmLet's see how to solve the problem step by step.1. Initialize a list with negative and positive numbers. 2. Write a lambda expression the takes a list as an argument.    2.1. Iterate over the list and get negative numbers    2.2. Same for positive numbers    2.3. Combine both using concatination operator. 3. Return the resultant list.Note - Use ... Read More

In this tutorial, we are going to learn how to use dictionary comprehensions in Python. If you are already familiar with list comprehension, then it won't take much time to learn dictionary comprehensions.We need the key: value pairs to create a dictionary. How to get these key-value pairs using dictionary comprehension? See the general statement of dictionary comprehension.{key: value for ___ in iterable}We need to fill in the above statement to complete a dictionary comprehension. There are many ways to fill it. Let's see some of the most common ways.Let's see how to generate numbers as keys and their squares ... Read More