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Articles on Trending Technologies
Technical articles with clear explanations and examples
Count the number of possible triangles in C++
We are given an array which contains the length of sides of triangles. The goal is to find the number of possible triangles that can be made by taking any three sides from that array.We will do this by checking if the sum of any two is always > third side. If yes these three sides can make a triangle. Increment count of possible triangles that can be made.Let’s understand with examples.Input − arr[]= {1, 2, 4, 5}Output − Count of possible triangles − 1Explanation − Sides (2, 4, 5) can only make a triangle as 2+4>5 & 4+5>2 & ...
Read MoreHow to add a new column to an R data frame with largest value in each row?
When we have a data frame that contains all numerical columns then we might want to find the largest value in each row. For example, if we have a sales data set in which each row represents a customer and columns represent the products with quantities of values as values then we might want to find the maximum of each row to find out who buys which product the most. This can be done by using max with apply function for rows.ExampleConsider the below data frame −> x1 x2 x3 x4 x5 df1 df1Output x1 ...
Read MoreMaximum number of unique prime factors in C++
Given the task is to find the maximum number of unique prime factors a number can have in the range of [1, N] where N is given.Let’s now understand what we have to do using an example −Input − N=100Output − 3Explanation − Let us take 30 in the range of [1, 100]30 = 3 * 2 * 5 = unique prime factors. Therefore, in the range of [1, 100] a maximum of 3 unique factors can be found.Input − N=300Output − 4Approach used in the below program as followsIn function MaxPrime() we will first check if (N < 2). ...
Read MoreCount the number of pairs (i, j) such that either arr[i] is divisible by arr[j] or arr[j] is divisible by arr[i] in C++
We are given with an array arr[] of N elements. The goal is to find the count of all valid pairs of indexes (i, j) such that either arr[i] is divisible by arr[j] or arr[j] is divisible by arr[i] and i!=j.We will do this by traversing the array arr[] using two for loops for each number of pair and check if arr[i]%arr[j]==0 or arr[j]%arr[i]==0 when i!=j. If true increment count of pairs.Let’s understand with examples.Input − Arr[]= { 2, 4, 3, 6 } N=4Output − Count of valid pairs − 3Explanation − Valid pairs are −Arr[0] & Arr[1] → (2, ...
Read MoreHow to change the color and size of the axes labels of a plot created by using plot function in R?
The default size of axes labels created by using plot function does not seem to be large enough and also it does not look appealing. Therefore, we might want to change their size and color because the appearance of a plot matters a lot. This can be done by setting colors with col.lab and size with cex.lab.Example> x y plot(x,y)OutputChanging the color of axes labels and the size of those axes labels −> plot(x,y,col.lab="blue",cex.lab=2)Output> plot(x,y,col.lab="dark blue",cex.lab=3)Output
Read MoreCount the number of pairs that have column sum greater than row sum in C++
We are given a matrix of size NXN. The goal is to find the count of all valid pairs of indexes (i, j) such that the sum elements of column j is greater than the sum of elements of row i.We will do this by traversing the matrix and calculate sums of elements of each row and column.Store sum of elements of each in rowsum[N] and sum of elements of each column in colsum[N].Now make pairs of rowsum[i] and colsum[j] and check if colsum[j]>rowsum[i]. If true increment count for such pairs.Let’s understand with examples.Input-: matrix= { { 1, 2, ...
Read MoreHow to select rows based on range of values of a column in an R data frame?
Extraction or selection of data can be done in many ways such as based on an individual value, range of values, etc. This is mostly required when we want to either compare the subsets of the data set or use the subset for analysis. The selection of rows based on range of value may be done for testing as well. We can do this by subset function.ExampleConsider the below data frame −> x1 x2 x3 df dfOutput x1 x2 x3 1 3 2 6 2 3 4 9 3 4 4 12 4 4 8 12 5 3 5 11 6 ...
Read MoreCount the number of operations required to reduce the given number in C++
We are given with a positive integer K and an array Ops[] which contains integers. The goal is to find the number of operations required to reduce K such that it becomes less than 0. Operations are −First operation is K + Ops[0], first element added to KAfter 1. Add Ops[i] to K until K
Read MoreHow to draw gridlines in a graph with abline function in R?
Gridlines are the horizontal and vertical dotted lines, and they help to organize the chart so that the values on the labels becomes better readable to viewers. This is helpful specially in situations where we plot a large number of data points. A graph drawn by plot function can have gridlines by defining the vertical and horizontal lines using abline.ExampleConsider the below data and scatterplot −> x y plot(x,y)OutputAdding gridlines using abline function −> abline(h=seq(0,5,0.5),lty=5) > abline(v=seq(-2,2,0.5),lty=5)Output
Read MoreHow to concatenate column values and create a new column in an R data frame?
Sometimes we want to combine column values of two columns to create a new column. This is mostly used when we have a unique column that maybe combined with a numerical or any other type of column. Also, we can do this by separating the column values that is going to be created with difference characters. And it can be done with the help of apply function.ExampleConsider the below data frame −> ID Country df1 df1Output ID Country 1 1 UK 2 2 UK 3 3 India 4 4 USA 5 5 USA 6 6 UK 7 7 Nepal 8 8 ...
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