Multiples of 3 and 5 Without Using Operator in C++

We can find the multiples using % operator without any hurdles. But, the problem states that we can't use % operator.

Here, we make use of the + operator. We can get the multiples by adding 3 or 5 to the previous multiple. Let's see an example.

Input

15

Output

1
2
3 - Multiple of 3
4
5 - Multiple of 5
6 - Multiple of 3
7
8
9 - Multiple 3
10 - Multiple of 5
11
12 - Multiple of 3
13
14
15 - Multiple of both 3 and 5

Algorithm

• Initialise the number n.

• Initialise two number to keep track of next multiple of 3 and 5.

• Initially those two numbers will be 3 and 5.

• Write a loop that iterates from 1 to n. Both inclusive.

  • Check whether the current number is multiple of 3 or not using the track variably.

  • Similarly check for the multiple of 5.

  • If they are multiple of 3 or 5, add respective number to them to get the next multiple.

  • Print the corresponding text to the console.

Implementation

Following is the implementation of the above algorithm in C++

#include <bits/stdc++.h>
using namespace std;
void findMultiplesOf3And5(int n) {
   int threeMultiple = 3;
   int fiveMultiple = 5;
   for (int i = 1; i <= n; i++) {
      bool _3 = false, _5 = false;
      if (i == threeMultiple) {
         threeMultiple += 3;
         _3 = true;
      }
      if (i == fiveMultiple) {
         fiveMultiple += 5;
         _5 = true;
      }
      if (_3 && _5) {
         cout << "Multiple of both 3 and 5" << endl;
      }else if (_3) {
         cout << "Multiple of 3" << endl;
      }else if (_5) {
         cout << "Multiple of 5" << endl;
      }else {
         cout << i << endl;
      }
   }
}
int main() {
   findMultiplesOf3And5(100);
   return 0;
}

Output

If you run the above code, then you will get the following result.

1
2
Multiple of 3
4
Multiple of 5
Multiple of 3
7
8
Multiple of 3
Multiple of 5
11
Multiple of 3
13
14
Multiple of both 3 and 5
16
17
Multiple of 3
19
Multiple of 5
Multiple of 3
22
23
Multiple of 3
Multiple of 5
26
Multiple of 3
28
29
Multiple of both 3 and 5
31
32
Multiple of 3
34
Multiple of 5
Multiple of 3
37
38
Multiple of 3
Multiple of 5
41
Multiple of 3
43
44
Multiple of both 3 and 5
46
47
Multiple of 3
49
Multiple of 5
Multiple of 3
52
53
Multiple of 3
Multiple of 5
56
Multiple of 3
58
59
Multiple of both 3 and 5
61
62
Multiple of 3
64
Multiple of 5
Multiple of 3
67
68
Multiple of 3
Multiple of 5
71
Multiple of 3
73
74
Multiple of both 3 and 5
76
77
Multiple of 3
79
Multiple of 5
Multiple of 3
82
83
Multiple of 3
Multiple of 5
86
Multiple of 3
88
89
Multiple of both 3 and 5
91
92
Multiple of 3
94
Multiple of 5
Multiple of 3
97
98
Multiple of 3
Multiple of 5