Suppose we have one 2D array of size N x M. The task is to check if we can select a number from every row, in such a way that the XOR of those elements is non-zero or greater than 0. Suppose one matrix is like this −77710107If we perform XOR, the answer will be non-zero, as the except last elements of two rows are 7 and 10To solve this problem, the solution will be very easy. Initially check if XOR of the elements of the first column of each row is 0 or not. If it is non-zero then ... Read More

Here we will see how to check whether a matrix is invertible or not. If one matrix is M, then the inverted matrix M-1 will be −$$M^-1=\frac{adj(M)}{|M\lvert}$$So if the determinant of M is non-zero, then only we can get the inverse, otherwise, we will not get the inverse of it. So here we have to check the determinant is non-zero or not. Finding a determinant is one recursive process. We have to find submatrix, then find the determinant of it, then use that result for the final calculation. Let us see the code to get a better idea.Example Live Demo#include ... Read More

Suppose we have a circle and another straight line. Our task is to find if the line touches the circle or intersects it, otherwise, it passes through outside. So there are three different cases like below −Here we will solve it by following steps. These are like below −Find perpendicular P between the center and given a lineCompare P with radius r −if P > r, then outsideif P = r, then touchesotherwise insideTo get the perpendicular distance, we have to use this formula (a center point is (h, k))$$\frac{ah+bk+c}{\sqrt{a^2+b^2}}$$Example Live Demo#include #include using namespace std; void isTouchOrIntersect(int a, ... Read More

Suppose we have a graph. We have to check whether the graph is strongly connected or not using Kosaraju algorithm. A graph is said to be strongly connected, if any two vertices has path between them, then the graph is connected. An undirected graph is strongly connected graph.Some undirected graph may be connected but not strongly connected. This is an example of strongly connected graph.This is an example of connected, but not strongly connected graph.Here we will see, how to check a graph is strongly connected or not using the following steps of Kosaraju algorithm.Steps −Mark all nodes as not ... Read More

Here we will see how to check whether a tree graph is linear or not. A linear tree graph can be expressed in one line, suppose this is an example of a linear tree graph.But this is not linear −To check a graph is linear or not, we can follow two conditionsIf the number of nodes is 1, then the tree graph is linearIf (n – 2) of its nodes have in-degree 2Example Live Demo#include #include #define N 4 using namespace std; class Graph{    private:    int V;    vector *adj;    public:    Graph(int v){     ... Read More

Here we will see how to check whether a string is sum-string or not. A string is said to be sum-string if the rightmost substring can be written as the sum of two substrings before it, and the same is recursively true for substring before it. Suppose a string like 12243660 is a sum string, like 12 + 24 = 36, and the 36 is present after 12 and 24 in the string, again 24 + 36 = 60, this is also present in the string.A string S can be called sum-string, if it follows this rule −𝑠𝑢𝑏𝑠𝑡𝑟𝑖𝑛𝑔(𝑖, 𝑥)+𝑠𝑢𝑏𝑠𝑡𝑟𝑖𝑛𝑔(𝑥+1, 𝑗)= ... Read More

We have two circles. The center of both of them is at the origin. The radius of these two circles is given. They are r and R, R > r. Another circle is also present. Its radius (r1) and the center point are given, we have to check whether that point is inside the ring formed by the first two circles or not.We can solve this using the Pythagorean theorem. compute the distance from the center of the circle and origin. Then if (distance – r1) >= r and (distance – r1) = R && dis+r1

Here we will see how to check whether a binary tree is sum-tree or not. Now the question is what is the sum-tree. A sum-tree is a binary tree where a node will hold the sum value of its children. The root of the tree will contain an entire sum of all elements below it. This is an example of sum-tree −To check this, we will follow a simple trick, we will find the sum of left and right subtree elements if the sum value is the same as the root, then that is sum-tree. This will be one recursive ... Read More

Here we will see how to check whether an unsorted array has duplicate elements within k distance from each other or not. Suppose a list of elements is {1, 2, 3, 1, 4, 5}, here if k = 3, then the program will return true, as the distance between two 1s is 3.We will solve this using a hash table. The steps will be like below −Create one empty hash tableFor each index i, let the element e = arr[i] in the list, doif e is present in the hash table, then return trueotherwise, add e to hash table, and ... Read More

Here we will see how to check a string is a palindrome or not using a Doubly linked list. Here we will push each character of a string inside one doubly linked list. There will be two pointers, left and right. Then start scanning from both sides. If a left character is the same as right character, then move the left pointer to the next node, and move the right pointer to the previous node. Otherwise, return false. This process will be continued until the left and right are pointing at the same node, or the right pointer is pointing ... Read More