I am writing a program in which I am asking a user for long long int. After the user has provided me with a number, I want to add every other digit in that number, starting from the second digit. Now my question is, how can I select every other digit in long long int? (C language)
Given a integral type number n, n % 100 / 10 will extract the second to last digit. This expression is a touchstone for your knowledge of operator precedence and associativity.
You'll need to use n % 10 and n / 10 to extract and subsequently remove the last digit if the number of digits in the number is even (search around on this site for adequate algorithms to count the number of digits in a number).
n / 100 will remove the final two digits.
Put the above into a loop, and you're done.
You can do :-
#include<stdio.h>
int main()
{
long real_Number,num,arr[100],count=0;
scanf("%ld",&real_Number);
do{
if(real_Number>99)
{
num=real_Number%100;
num=num/10;
arr[count]=num;
real_Number=real_Number/100;
++count;
}
if(real_Number<100)
{
arr[count]=real_Number/10;
break;
}
}while(real_Number>=10);
}
Note : The Digits stored in array are backward for example 123456 results in
arr[0]=5, arr[1]=3 ,arr[2]=1;
To print:-
for(count; count>=0 ;count--)
{
printf("%ld",arr[count]);
}
Related
I am doing this problem:
"We have a huge decimal number N. Write a program to determine the followings:
The number of digits in N.
Is N an even number?
The number of zeros in it.
Is N a multiple of 11? Note that we can determine if N is a multiple of 11 by checking the difference between the sum of the odd positioned digits and the sum of the even positioned digits. For example, 82375 is not a multiple of 11 because the sum of the even positioned digits is 2 + 7 = 9, and the sum of the odd positioned digits is 8 + 3 + 5 = 16, and the difference between 9 and 16 is 7, which is not a multiple of 11.
We will give you the number one digit per line. For example, if you get digits ‘1’, ‘2’, ‘3’, ’4’, ‘0’ in order, then the number is 12340. The number will not start with 0.
Input Format
The input has several lines. Each line has a digit. EOF indicates the end of input.
Output Format
Output the four answers above line by line. If the number is even output a 1; otherwise a 0. If the number is a multiple of 11 output a 1; otherwise output a 0.
Subtask
10 points: you can store the decimal number in an integer without overflow
10 points: the number of digits is no more than 32768, so you can store digits in an array
80 points: you will get MLE if you use array"
my code is:
#include <stdio.h>
#include <stdbool.h>
int digit(long n);
int is_even(int n);
int count_zeros(long n);
int is_multiple(long n);
int main() {
int digits = 0;
long x;
scanf("%ld", &x);
digit(x);
int even = is_even(x);
printf("%d\n", even);
printf("%ld\n",count_zeros(x));
printf("%ld\n", is_multiple(x));
}
int digit(long n)
{
int digits = 0;
while (n > 0) {
n /= 10;
digits++;
}
printf("%ld\n", digits);
}
int is_even(int n)
{
if (n % 2 == 0)
return true;
else
return false;
}
int count_zeros(long n)
{
int count = 0;
while (n > 0) {
n /= 10;
if (n %10 == 0)
count++;
}
return count;
}
int is_multiple(long n)
{
if (n % 11 == 0) {
return true;
}
else
return false;
}
Basically i dont know how to meet the problem's requirement, so I made a simpler version of the problem. Any clue on how to do this?
If you comment on this, please be nice, I am a beginner and people was rude in the past,if you have nothing important to say, do not be mean/do not comment.
Well, the first problem with your current version is it only reads one integer. However problem states that each digit is on a separate line. The first approach may be to just replace that scanf with a loop and keeping multiplying by 10 and accumulating until end of file. Then the rest of the program would work fine.
A more advanced approach will be to use an array to store the digits. An integer can hold a very limited number of digits whereas you are only bounded with the size of available memory using array.
So in the reading loop rather than storing digits in an integer, you can store digits in an array (which could be fixed size because an upper limit is given). But for the rest of the program you should change the calculation to use digits in the array instead of the regular integer arithmetic.
Problem:
You are provided an array A of size N that contains non-negative integers. Your task is to determine whether the number that is formed by selecting the last digit of all the N numbers is divisible by 10.
Note: View the sample explanation section for more clarification.
Input format
First line: A single integer N denoting the size of array Ai.
Second line: N space-separated integers.
Output format:
If the number is divisible by 10 , then print Yes . Otherwise, print No.
Constraints:
1<=N<=100000
0<=A[i]<=100000
i have used int, long int ,long long int as well for declaring N and 'm'.But the answer was again partially accepted.
#include <stdio.h>
int main() {
long long int N,m,i;
scanf("%ld", &N);
long data[N];
for(auto i=0; i<N; i++) {
scanf("%ld", &data[i]);
}
// write your code here
// ans =
m=(data[0]%10);
for(i=1; i<N; i++) {
m=m*10;
m=(data[i]%10)+m;
}
if(m%10!=0 && m==0) {
printf("Yes");}
else{
printf("No");
}
return 0;
}
Try making a test suite, that is, several tests for which you know the answer. Run your program on each of the tests; compare the result with the correct answer.
When making your tests, try to hit also corner cases. What do I mean by corner cases? You have them in your problem statement:
1<=N<=100000
0<=A[i]<=100000
You should have at least one test with minimal and maximal N - you should test whether your program works for these extremes.
You should also have at least one test with minimal and maximal A[i].
Since each of them can be different, try varying them - make sure your program works on the case where some of the A[i] are large and some are small.
For each category, include tests for which the answer is Yes and No - to exclude the case where your algorithm always outputs e.g. Yes by mistake.
In general, you should try to make tests which challenge your program - try to prove that it has a bug, even if you believe it's correct.
This code overflows:
m=(data[0]%10);
for(i=1; i<N; i++) {
m=m*10;
m=(data[i]%10)+m;
}
For example, when N is 1000, and each of the input items A[i] (scanned into data[i]) ends in 9, this attempts to compute m = 99999…99999, which grossly overflows the capability of the long long m.
To determine whether the numeral formed by concatenating a sequence of digits is divisible by ten, you merely need to know whether the last digit is zero. The number is divisible by ten iff data[N-1] % 10 == 0. You do not even need to store these numbers in an array; simply use scanf to read but ignore N−1 numerals (e.g., scanf("%*d")), then read the last one and examine its last digit.
Also scanf("%ld", &N); wrongly uses %ld for the long long int N. It should be %lld, or N should be long int.
An integer number given in decimal is divisible by ten if, and only if, its least significant digit is zero.
If this expression from your problem:
the number that is formed by selecting the last digit of all the N numbers
means:
a number, whose decimal representation comes from concatenating the least significant digits of all input numbers
then the last (the least significant) digit of your number is the last digit of the last input number. And that digit being zero is equivalent to that last number being divisible by 10.
So all you need to do is read and ignore all input data except the last number, then test the last number for divisibility by 10:
#include <stdio.h>
int main() {
long N, i, data;
scanf("%ld", &N);
for(i=0; i<N; i++)
scanf("%ld", &data); // scan all input data
// the last input number remains in data
if(data % 10 == 0) // test the last number
printf("Yes");
else
printf("No");
return 0;
}
C language question.
My task is to get second to the last, third to the last digit etc. from a long.
Got a hint to do it by using modulo operator:
int main(void)
{
a = get_long("n:\n");
mod = a % 10;
printf("%i", mod);
}
Works great for the rightmost digit but I just can't figure it out how to get second-, third-to the last digit, and so on.
I am trying to put the function into a for loop but it does not work at all.
Do you have any ideas how to accopmlish that?
I am not looking for a ready solution - just for the path to follow.
You started off right, the first iteration will give you the rightmost digit. After that, you need to reduce the original number in a way such that the one but last number becomes the last one.
Solution: Divide by 10. Every time you divide the number by 10 (integer division), the rightmost digit disappears and the last but one digit becomes the last digit. So, you can keep using the same login with modulo to obtain the new last digit.
Something like
int main(void)
{
int a = get_long("n:\n"); //why no datatype?
int mod = -1;
for (; a > 0; a/=10){ // check if a> 0, perform the modulo, and then divide by 10
mod = a % 10;
printf("%i\n", mod);
}
}
This question is asked in one of codechef competitions.I have tried it in c. Below is my code:
scanf("%d",&N);
count=0;
for(i=2;i<=N;i++)
{
c=a;
while(c>=i)
{
c=c/i;
}
if(b==1)
count++;
}
printf("%d\n",count);
But this is giving me only partial marks. Can it be solved in lesser time? If so, how?
The smallest number with a leading 1 and d digits in base b is 10...0 which is b^(d-1).
The largest such number is 2*b^(d-1)-1. Thus the bases such that a given number N falls inside that range are given by the inequalities
pow(0.5*(N+1), 1.0/(d-1) ) <= b <= pow(N, 1.0/(d-1) )
With appropriate rounding, taking into account random floating point errors, you can directly count how many integer b are inside these boundaries.
Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 8 years ago.
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I'm new to C. I have a class assignment to display a number in a vertical format. If the user enters 5678, the instructor want it to display vertically to the screen in a single column as:
8
7
6
5
Second part of assignment is to find the largest divisor of the same number.
I'm totally lost. I'm getting the NUM value from another function. formula seems to work on even numbers, but on odd.
int divisor (int NUM)
{
int index, count=0;
for(index=2;index<=(NUM/2);index=index+1)
{
if(NUM%index==0)
count++;
}
printf("\n\nThe largest divisor of %d is %d\n",NUM, index-1);
return(index);
}
To display the number vertically:
1. get least significant digit,
2. print it and print new line,
3. shift number to the right by one digit
4. goto 1
Algorithm terminates when the number is zero. Call the input number n; getting the least significant (rightmost) digit can be done with n % 10. Right shift can be done with n = n / 10.
For the second part, observe that the largest divisor cannot be more than n/2 (because n = 2 * n/2). So try all number from n/2 down to 1 and break once you find a divisor. You will find the largest divisor because you are considering numbers in decreasing order. To check that x divides y use y % x == 0.
A second way it to check numbers from sqrt(n) down to 1. If m divides n, we can write n = m * k for some k. Now you take max(m, n/m) and continue.
Hope this helps :)
For the first part, there are many ways to approach this. But, without using too many of the standard library functions which seems to be a level appropriate for the question, I think the easiest way would be to take the numbers as a character array. Then access each value through it's index in the character array. This requires only the stdio.h header file. Some quick notes: simply use printf to print the value contained at each index, and throw the newline \n character at the end. If you wanted convert the string to an integer, you can do that very easily using the function atoi() which can be found in stdlib.h. If you want to print out backward, you can simply traverse the array backward.
void displayvert(char str[])
{
int i;
for (i = 0; str[i] != '\0'; ++i) {
printf("%c\n", str[i]);
}
}
Also many ways to approach the second, but in this case for the second question I think I'd use the modulus operator and track the highest value where the result is zero. In order for this to work with the single user provided input, I actually needed atoi() which is in the stdlib.h header. Basically, starting from the value one you'll increase the value up the integer just below the value of 'num' itself. And, if the remainder is zero when you when you divide by it (the purpose of using the modulus operator) then you know it's divisible. Because we're ascending from 1 to the number itself, the last value to return a remainder of zero is the greatest common divisor.
void getgcd(int num)
{
int i, gcd;
// remember, you can't do x % 0!
for (i = 1; i < num; i++) {
if ((num % i) == 0 ) {
gcd = i;
}
}
printf("The greatest common divisor is: %d\n", gcd);
}
Main function and prototypes here so you can see how it all tied together. A couple of quick notes (1) 11 digits was arbitrary; but it's important to note that we used 10 digits for the total input value (you can add checks to this to enforce) and reserved the 11th (at index 10) to allow space for the null terminating character \0. (2) Use scanf to grab input; note that because character arrays do not require the address operator & because it defaults to that.
#include <stdio.h>
#include <stdlib.h>
void displayvert(char str[]);
void getgcd(int num);
int main()
{
char input[11]; // additional character added for \0
printf("Please enter a value up to 10 digits: ");
scanf("%s", input);
displayvert(input);
getgcd(atoi(input));
return 0;
}