C++ program help obtaining all natural numbers

Question

1.00/5 (2 votes)

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I have a task to write a program in C ++ with the following condition: To write a program for obtaining all natural numbers not exceeding a given n, which represent a strictly increasing sequence of digits. I will be very grateful if you help me with the code.

What I have tried:

#include <iostream>
int main()
{
	using namespace std;

	int n;
	cin >> n;

	for (int i = 1; i <= n; i++)
	{
	}

	return 0;
}

Posted 19-Nov-21 0:21am

DeathHourBG

Updated 23-Nov-21 0:52am

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Comments

Richard MacCutchan 19-Nov-21 7:09am

That is just a simple matter of counting from 1 to n.

5 solutions

Solution 4

This function:

C++

#include <iostream>
bool isStrictlyIncreasing(int x) {
    // check consecutive digits, from right to left:
    // start by checking last digits
    int lastDigit = x % 10;
    int leadingDigits = x / 10;
    while (leadingDigits > 0) {
        int digit = leadingDigits % 10; // digit before lastDigit
        if (digit >= lastDigit)
            return false;
        // move test window one digit to the left
        lastDigit = digit;
        leadingDigits = leadingDigits / 10;
    }
    return true;
}
int main()
{
    int tests[] {2, 11, 13, 20, 123, 120, 1243, 2334};
    for (int i = 0; i < 8; ++i) {
        std::cout<< tests[i] << " is increasing: " << isStrictlyIncreasing(tests[i]) << "\n";
    }
    char c;
    std::cin >> c;

    return 0;
}

returns this output:

2 is increasing: 1
11 is increasing: 0
13 is increasing: 1
20 is increasing: 0
123 is increasing: 1
120 is increasing: 0
1243 is increasing: 0
2334 is increasing: 0

Is that what you were looking for?

Posted 22-Nov-21 7:23am

Stefan_Lang

Solution 1

We are more than willing to help anyone who is genuinely stuck, but we will not write your homework assignment for you and you have made no effort to solve this for yourself.

Here is a site that will give you the definition of natural numbers and how to find them Natural Numbers - Concepts, Properties, Number Line & Examples[^]
Here is an article that should help you get started on a solution How to Write Code to Solve a Problem, A Beginner's Guide[^]

Start coding, give it a go and if you get stuck then please do come back here with your code, explain your problem and we will try to help

Posted 19-Nov-21 1:04am

CHill60

Solution 3

Quote:
but I can't do "which is a strictly ascending sequence of numbers"

The key is to split the number into digits.

C++

int number=123;
int unit= number % 10; // unit= 3
int rest= number / 10; // rest= 12

Posted 19-Nov-21 3:45am

Patrice T

Solution 5

By construction:

C++

#include <iostream>
using namespace std;

void add_dgt(int num, int dgt, int limit)
{
  num *= 10;
  for (; dgt < 10; ++dgt)
  {
    if (( num + dgt ) <= limit)
      cout << (num + dgt) << endl;

    if ( dgt < 9 )
    {
      add_dgt( num + dgt, dgt + 1, limit);
    }
  }
}

int main()
{
  int limit;
  cout << "please enter the limit ";
  cin >> limit;

  if (limit > 0 )
    add_dgt(0, 1, limit);
}

Posted 23-Nov-21 0:52am

CPallini

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DeathHourBG · Accepted Answer · 2021-11-19T01:48:00

Solution 2

As you can see above I've made the code somewhere, but I can't do "which is a strictly ascending sequence of numbers"

#include <iostream>
int main()
{
	using namespace std;

    bool isStrictlyIncreasing( int x )
	int n;
	cin >> n;

	for (int i = 1; i <= n; i++)
	{
		if ( isStrictlyIncreasing( i ) ) cout << i << '\n';
	}

	return 0;
}

Posted 19-Nov-21 1:48am

DeathHourBG

Updated 19-Nov-21 2:16am

v2

Comments

Richard MacCutchan 19-Nov-21 8:48am

I have no idea what that is supposed to be, but as I already suggested, all you need is a simple loop that counts from 1 to n.

Stefan_Lang 22-Nov-21 11:00am

The OP says "natural numbers that have a strictly increasing sequence of digits". So 1, 2, 3, and 12 would be in, but 10 and 11 would be out because their digits are not increasing.

Richard MacCutchan 22-Nov-21 11:23am

I don't understand where the out of sequence numbers come from.

Stefan_Lang 22-Nov-21 12:09pm

The number 10 has digits 1 and 0, so the digits are decreasing.
The number 12 has digits 1 and 2, so the digits are strictly increasing.

12 fulfils the criterium, 10 doesn't.

Richard MacCutchan 22-Nov-21 12:37pm

Thanks, I misunderstood the question, despite reading it a number of times.

Stefan_Lang 22-Nov-21 10:58am

Please don't post extensions to your original question as a solution, specifically if it isn't a solution.