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Here we will check whether a number is positive, or negative or zero using bit operators. If we perform shifting like n >> 31, then it will convert every negative number to -1, every other number to 0. If we perform –n >> 31, then for positive number it will return -1. When we do for 0, then n >> 31, and –n >> 31, both returns 0. for that we will use another formula as below −1+(𝑛>>31)−(−𝑛>>31)So now, ifn is negative: 1 + (-1) – 0 = 0n is positive: 1 + 0 – (-1) = 2n is 0: ... Read More
Suppose a number is given, we have to check whether the number is a perfect square or not. We will not use the square root operation to check it. Suppose a number 1024 is there, this is a perfect square, but 1000 is not a perfect square. The logic is simple, we have to follow this algorithm to get the result.AlgorithmisPerfectSquare(n) −input − The number noutput − true, if the number is a perfect square, otherwise, falsebegin for i := 1, i2 ≤ n, increase i by 1: if n is divisible by i, and n ... Read More
Here we will see how to check a number is divisible by 5 or not. One simple approach is that if the number mod 5 = 0, then, the number is divisible by 5. But here we will not use / or % operator. To check whether a number is divisible by 5, we have to see the last number is 0 or 5. If that is 0 or 5, the number is divisible by 5, otherwise not. Here we can use some large numbers also as a string to check.Example#include using namespace std; bool isDiv5(string num){ int ... Read More
Here we will see one interesting problem to check whether a number is jumbled or not. A number is said to be jumbled if, for every digit, it's neighbor digit differs by max 1. For example, a number 1223 is jumbled, but 1256 is not jumbled.To solve this problem, we have to check if a digit has a neighbor with a difference greater than 1. If such digit is found, then return false, otherwise true.Example Live Demo#include #include using namespace std; bool isJumbled(int number) { if (number / 10 == 0) //for single digit number is is always ... Read More
Suppose, we have a number string, we have to find that the number is of given base B or not? If the string is “101110”, b = 2, then the program will return true. If the string is “A8F”, base is 16, it will be true.The approach is very simple. If all of the character is in the range of symbols of the given base, then return true, otherwise false.Example Live Demo#include using namespace std; bool inGivenBase(string s, int base) { if (base > 16) //program can handle upto base 1 return false; ... Read More
We have an array A, we have to check whether the array can represent a BST with n levels or not. As the level is , we can construct a tree in following manner. Assume a number is k, value greater than k moves to right side, and less than k moves to left side. Suppose two lists are there: {50, 20, 9, 25, 10}, and {50, 30, 20, 25, 10}The first one is not valid, but the second one is valid.To check this we can either create a BST and check the height, otherwise use array based approach. The ... Read More
Here we will see, if a matrix is magic square or not, a magic square is a square matrix, where the sum of each row, each column, and each diagonal are same.Suppose a matrix is like below −618753294This is a magic square, if we see, the sum of each row, column and diagonals are 15.To check whether a matrix is magic square or not, we have to find the major diagonal sum and the secondary diagonal sum, if they are same, then that is magic square, otherwise not.Example Live Demo#include #define N 3 using namespace std; bool isMagicSquare(int mat[][N]) { ... Read More
Consider we have a 2D array. We have to find if we can get a path from topleft corner to bottom-right corner. The matrix is filled with 0s and 1s. 0 indicates open area, 1 indicates blockage. Note that the top-left corner will always be 1.Suppose a matrix is like below −0001010011000101000000100One path is marked as green, there are some other paths also. So the program will return true, if there is a path, otherwise false.We will solve this problem, by changing all accessible node to -1, First change the value of starting point to -1, then get next value ... Read More
Consider we have a string and some queries in set Q. Each query contains a pair of integers i and j. and another character c. We have to replace characters at index i and j with the new character c. And tell if the string is palindrome or not. Suppose a string is like “AXCDCMP”, if we use one query like (1, 5, B), then the string will be “ABCDCBP”, then another query like (0, 6, A), then it will be “ABCDCBA”, this is palindrome.We have to create one query using indices i, j, then replace the characters present at ... Read More
Suppose we have an array; we have to check whether given number x is the majority element of that array or not. The array is sorted. One element is said to be majority element, when it appears n/2 times in the array. Suppose an array is like {1, 2, 3, 3, 3, 3, 6}, x = 3, here the answer is true as 3 is the majority element of the array. There are four 3s. The size of the array is 7, so we can see 4 > 7/2.We can count the occurrences of x in the array, and if ... Read More