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Articles by Arnab Chakraborty
Page 306 of 377
Check if a large number is divisible by 9 or not in C++
Here we will see how to check a number is divisible by 9 or not. In this case the number is very large number. So we put the number as string.A number will be divisible by 9, if the sum of digits is divisible by 9.Example#include using namespace std; bool isDiv3(string num){ int n = num.length(); long sum = accumulate(begin(num), end(num), 0) - '0' * n; if(sum % 9 == 0) return true; return false; } int main() { string num = "630720"; if(isDiv3(num)){ cout
Read MoreCheck if a number can be expressed as 2^x + 2^y in C++
Here we will see, if we can represent a number as sum of two non-zero powers of 2. So we will check the given number N can be represented as (2x + 2y) where x, y > 0. Suppose a number is 10, this can be represented as 23 + 21.The approach is simple. There are two cases. If the number n is even, it can be represented as 2x. Where x > 0. Another case is that is N is odd, it can never be represented as sum of powers of 2. We cannot use power as 0, so ...
Read MoreCheck if a number can be expressed as a^b in C++
Here we will check whether we can represent a number like ab or not. Suppose a number 125 is present. This can be represented as 53. Another number 91 cannot be represented as power of some integer value.AlgorithmisRepresentPower(num): Begin if num = 1, then return true for i := 2, i2
Read MoreSort an array according to the order defined by another array in C++
In this section we will see another sorting problem. Suppose we have two arrays A1 and A2. We have to sort A1 in such a way that the relative order among the elements will be same as those are in A2. If some elements are not present in A2, then they will be appended after the sorted elements. Suppose A1 and A2 are the following −A1 = {2, 1, 2, 1, 7, 5, 9, 3, 8, 6, 8} A2 = {2, 1, 8, 3}After the sorting A1 will be like below −A1 = {2, 2, 1, 1, 8, 8, 3, ...
Read MoreCheck if a given mobile number is fancy in C++
We have a 10 digit mobile number, our task is to check whether the number is fancy number or not. There are three different conditions for a fancy number. If at least one is true, then the number is fancy. These conditions are like below −A single number occurs three consecutive times, like 555Three consecutive numbers are either in increasing or decreasing order like 123 or 321.A single digit occurs four or more times in a number, like 8965499259, here 9 has occurred four times.One example of fancy number is 9859009976, this is a fancy number as the third condition ...
Read MoreCheck if a number can be represented as a sum of 2 triangular numbers in C++
In this section, we will see if we can express one number as the sum of two triangular numbers or not. The triangular numbers are like below −From the example, we can see that 1, 3, 6, 10 are some triangular numbers. We need to express a number N (say 16) as sum of two triangular numbers (6, 10).The approach is very simple. We have to get all triangular numbers less than N. Form a set from these values. Now we have to take a number say X from the set, and check whether N – X is present in ...
Read MoreCheck if a given number can be represented in given a no. of digits in any base in C++
Suppose we have a number n, and number of digits d. We have to check whether the number n can be represented as d digit number in any base from 2 to 32. Suppose the number n is 8, and d = 4, then this can be represented as 1000 in binary, here the d is 4.The idea is to check all bases one by one from 2 to 32. We can follow these steps to check the base.If the number is smaller than base, and digit is 1, then return trueif digit is more than one and number is ...
Read MoreCheck if a number can be written as sum of three consecutive integers in C++
In this section we will see, whether a number can be represented as tree consecutive numbers or not. Suppose a number is 27. This can be represented as 8 + 9 + 10.This can be solved in two different approach. The first approach is Naïve approach. In that approach, we have to check i + (i + 1) + (i + 2) is same as number or not. Another efficient approach is by checking whether the number is divisible by 3 or not. Suppose a number x can be represented by three consecutive 1s, then x = (y - 1) ...
Read MoreCheck if a number has same number of set and unset bits in C++
In this section we will check whether a number has same number of set bits and unset bits or not. Suppose the number 12 is there. Its binary representation is 1100. This has same number of 0s and 1s.The approach is simple. We will check each bit of the number, and if that is 1, then increase set_bit_count, and if it is 0, then increase unset_bit_count. Finally, if they are same, then return true, otherwise false.Example#include using namespace std; bool hasSameSetUnset(int n) { int set_count = 0, unset_count = 0; while(n){ if((n & 1) ...
Read MoreCheck if a given number is Pronic in C++
Here we will see, how to check whether a number is Pronic number or not. A number that can be arranged to form a rectangle, are called the pronic numbers. First few pronic numbers are: 0, 2, 6, 12, 20, 30, 42, 56, 72, 90, 110, 132, 156, 182, 210, 240, 272, 306, 342. The pronin numbers are product of two consecutive integers. So a pronic number n = x * (x + 1).Here we will check and generate some pronic numbers.Example#include #include using namespace std; bool isPronicNumber(int num) { for (int i = 0; i
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