Arnab Chakraborty

Arnab Chakraborty

3,768 Articles Published

Articles by Arnab Chakraborty

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Find the missing number in Geometric Progression in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 18-Dec-2019 205 Views

Suppose we have an array that represents elements of geometric progression in order. One element is missing. We have to find the missing element. So if arr = [1, 3, 27, 81], output is 9, as 9 is missing.Using binary search, we can solve this problem. We will go to the middle element, then check whether the ratio between middle and next to the middle is same as common ratio or not. If not, then missing element is present between indices mid and mid + 1. If the middle element is the n/2th element in the GP, then missing element ...

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Find the missing number in Arithmetic Progression in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 18-Dec-2019 270 Views

Suppose we have an array that represents elements of arithmetic progression in order. One element is missing. We have to find the missing element. So if arr = [2, 4, 8, 10, 12, 14], output is 6, as 6 is missing.Using binary search, we can solve this problem. We will go to the middle element, then check whether the difference between middle and next to the middle is same as diff or not. If not, then missing element is present between indices mid and mid + 1. If the middle element is the n/2th element in the AP, then missing ...

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Find the minimum distance between two numbers in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 18-Dec-2019 1K+ Views

Suppose we have one unsorted array A, and two numbers x and y. We have to find the minimum distance between x and y in A. The array can also contain duplicate elements. So if the array is A = [2, 5, 3, 5, 4, 4, 2, 3], x = 3 and y = 2, then the minimum distance between 3 and 2 is just 1.To solve this, we have to follow these steps, Traverse the array from left to right and stop if either x or y has found. Then store the index of that position into prevNow traverse ...

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Find number of cavities in a matrix in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 18-Dec-2019 182 Views

Consider one matrix is given. We have to find the number of cavities in the matrix. One element is denoted as cavity when all other elements surrounding it is greater than the element. So if the matrix is like −456715456So the output is 1.We simply check the surrounding elements and form the decision.Example#include #define MAX 100 using namespace std; int numberOfCavities(int array[][MAX], int n) {    int arr[n + 2][n + 2];    int count = 0;    for (int i = 0; i < n + 2; i++) {       for (int j = 0; j < ...

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Find the longest path in a matrix with given constraints in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 18-Dec-2019 604 Views

Suppose we have one square matrix of order n. It has all distinct elements. So we have to find the maximum length path, such that all cells along the path are in increasing order with a difference of 1. From one cell we can move to four directions. Left, Right, Top and Bottom. So if the matrix is like −129538467So the output will be 4. As the longest path is 6→7→8→ 9To solve this problem, we will follow this idea. We will calculate longest path beginning with every cell. Once we have got the longest for all cells, we return ...

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Find the last non repeating character in string in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 18-Dec-2019 285 Views

Suppose we have a string str. We have to find the last non-repeating character in it. So if the input string is like “programming”. So the first non-repeating character is ‘n’. If no such character is present, then return -1.We can solve this by making one frequency array. This will store the frequency of each of the character of the given string. Once the frequency has been updated, then start traversing the string from the last character one by one. Then check whether the stored frequency is 1 or not, if 1, then return, otherwise go for previous character.Example#include ...

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Find minimum x such that (x % k) * (x / k) == n in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 18-Dec-2019 241 Views

Given two positive integers n and k, and we have to find the positive integer x, such that (x % k)*(x / k) is same as n. So if the n and k are 4 and 6 respectively, then the output will be 10. So (10 % 6) * (10 / 6) = 4.As we know that the value of x % k will be in range [1 to k – 1] (0 is not included) Here we will find possible integer in the range that divides n and hence the given equation becomes: x = (n * k) / ...

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Find minimum steps required to reach the end of a matrix in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 18-Dec-2019 461 Views

Suppose we have a 2D matrix with positive integers. We have to find the minimum steps required to move from to the end of the matrix (rightmost bottom cell), If we are at cell (i, j), we can go to the cell (i, j+mat[i, j]) or (i+mat[i, j], j), We cannot cross the bounds. So if the matrix is like −212111111The output will be 2. Path will be (0, 0) →(0, 2) → (2, 2)Here we will use the Dynamic programming approach to solve this. Suppose we are at cell (i, j), we want to reach (n-1, n-1) cell. We ...

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Find the first, second and third minimum elements in an array in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 18-Dec-2019 295 Views

Suppose we have an array of n elements. We have to find the first, second and the third minimum elements in the array. First minimum is the minimum of the array, second min is minimum but larger than the first one, and similarly the third min is minimum but greater than second min.Scan through each element, then check the element, and relate the condition for first, second and third min elements conditions to solve this problem.Example#include using namespace std; int getThreeMins(int arr[], int n) {    int first = INT_MAX, sec = INT_MAX, third = INT_MAX;       for ...

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Find all elements in array which have at-least two greater elements in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 18-Dec-2019 403 Views

Suppose, we have an array of n numbers. We have to find all elements in array, which have at least two greater elements. If the array is like A = [2, 8, 7, 1, 5], then the result will be [2, 1, 5]To solve this, we will find second max element, then print all elements which is less than or equal to second max value.Example#include using namespace std; void searchElements(int arr[], int n) {    int first_max = INT_MIN, second_max = INT_MIN;    for (int i = 0; i < n; i++) {       if (arr[i] > first_max) ...

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