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Articles on Trending Technologies
Technical articles with clear explanations and examples
Count pairs (a, b) whose sum of squares is N (a^2 + b^2 = N) in C++
We are given a number N. The goal is to find ordered pairs of positive numbers such that the sum of their squares is N.We will do this by finding solutions to the equation a2+ b2 = N. Where a is not more than square root of N and b can be calculated as square root of (N-a2).Let’s understand with examples.Input N=100Output Count of pairs of (a, b) where a^3+b^3=N: 2Explanation Pairs will be (6, 8) and (8, 6). 62+82=36+64=100Input N=11Output Count of pairs of (a, b) where a^3+b^3=N: 0Explanation No such pairs possible.Approach used in the below program is as followsWe take integer N.Function squareSum(int ...
Read MoreCount pairs (i,j) such that (i+j) is divisible by both A and B in C++
We are given variables N, M, A and B. The goal is to find ordered pairs of positive numbers( i, j ) such that their sum is divisible by both A and B. And 1
Read MoreProgram to find Inorder Successor of a binary search tree in C++
Suppose we have a binary search tree BST and another value of a node, we have to find the in-order successor of that node in the BST. As we all know that the successor of a node p is the node with the smallest key greater than the value of p.So, if the input is likeAnd p = 1, then the output will be 2, To solve this, we will follow these steps −Define recursive method inorderSuccessor(), this will take root and pif root null, then:return nullif val of root val val){ return inorderSuccessor(root->right, ...
Read MoreWhat are the different types of point available in geom_point of ggplot2 package in R?
We can create a point chart using ggplot2 package but that point not necessarily to be in circular shape, we have twenty-five shape options for those points in ggplot2. While creating a point chart using ggplot2, we can use shape argument inside geom_point to see the difference among these twenty-five shapes.ExampleConsider the below data frame:> set.seed(1957) > x y df dfOutput x y 1 0.7028704 1.6664500 2 0.9672393 1.0456639 3 1.3102736 0.2495795 4 0.3389941 0.2141513 5 0.5867095 0.4417377 6 0.4257543 0.6533757 7 0.9106756 0.3611954 8 1.0444729 1.3770588 9 ...
Read MoreCount pairs from two arrays having sum equal to K in C++
We are given two arrays Arr1[] and Arr2[] and a number K. The goal is to find unique pairs of elements of both arrays such that their sum is K. Pairs will be of form ( Arr1[i], Arr2[j] ) where Arr1[i]+Arr2[j]==K.We will traverse using two loops for i and j. If sum (Arr1[i]+Arr2[j])==K. And the pair doesn’t exist in unordered_map. Add it to the map and increment count.Let’s understand with examples.Input Arr1[]={ 1, 3, 2, 4, 3, 2 }; Arr2[]={ 0, 2, 1, 2, 3 }; K=4Output Number of pairs with sum K : 4Explanation Pairs will be ( Arr1[0], Arr2[4] ) → ...
Read MoreHow to find the correlation coefficient between two data frames in R?
If two data frames in R have equal number of columns then we can find the correlation coefficient among the columns of these data frames which will be the correlation matrix. For example, if we have a data frame df1 that contains column x and y and another data frame df2 that contains column a and b then the correlation coefficient between df1 and df2 can be found by cor(df1, df2).Example1Consider the below data frame:> x1 x2 df1 df1Output x1 x2 1 39.56630 38.25632 2 39.43689 44.14647 3 40.80479 37.43309 4 ...
Read MoreCount square and non-square numbers before n in C++
We are given a number N. The goal is to find ordered pairs of positive numbers such that the sum of their cubes is N.Naive ApproachTraverse all numbers from 1 to N and check if it is a perfect square. If floor(sqrt(i))==ceil(sqrt(i)).Then the number is a perfect square.Efficient ApproachPerfect squares below N can be found using formula: floor(sqrt(N)).Let’s understand with examples.Input N=20Output Count of square numbers: 4 Count of non-square numbers: 16Explanation Square numbers are 1, 4, 9 and 16. Rest all are non-squares and less than 20.Input N=40Output Count of square numbers: 6 Count of non-square numbers: 34Explanation Square numbers are 1, 4, 9, 16, ...
Read MoreHow to subset nth row from an R data frame?
We can find subsets using many ways in R and the easiest way is to use single-square brackets. If we want to subset a row or a number of consecutive or non-consecutive rows then it can be directly done with the data frame name and the single-square brackets. For example, if we have a data frame called df and we want to subset 1st row of df then we can use df[1, ] and that’s it.ExampleConsider the below data frame:> set.seed(214) > x y z a b c q w df1 df1Outputx y z a b c q w 1 ...
Read MoreHow to convert a named vector to a list in R?
A named vector cannot be directly converted to a list because we would need to un-name the vector names and convert those names to names of the list elements. This can be done by using lapply function function. For example, suppose we have a named vector x then it can be converted to a list by using the command x x1 names(x1) x1OutputA B C D E F G H I J K L M N O P Q R S T U V W X Y Z 1 2 3 4 5 6 7 8 9 10 11 12 ...
Read MoreCount strings that end with the given pattern in C++
We are given an array of strings str[] and a pattern string pat. The goal is to find the string elements of str[] that have pattern pat at the end.We will traverse each string of str and compare last characters with pat. If they match incrementLet’s understand with examples.Input str[]={ “kittens”, “hens”, “deers”, “dogs” } pat=”ens”Output Strings that end with given pattern: 2Explanation Strings “kitt-ens” and “h-ens” end with “ens”.Input str[]={ “tickets”, “wickets”, “bats”, “cricket” } pat=”et”Output Strings that end with given pattern: 1Explanation Strings “wick-et” ends with “et”.Approach used in the below program is as followsWe string array str[] and a pattern string pat.N is ...
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