So i got the following task in C : the user input two integers, let's call them n1 and n2, so that n1<=n2.
The programm must print all the possible integers between n1 and n2 (n1 and n2 included),and that all the digits in the number are increasing in their value.
For example, if the user input 1234 and 1260, the programm will print 1236,1237,1238,1239, but not 1240, since 0 is smaller than 4.
Then it will print 1356,1357,1358,1359.
I'm not allowed to use arrays (otherwise it would be very easy), functions, even the power function.
So I came up with the next pseudo code:
Make a loop that takes the number n1, and counts the number of digits it has.
Then make a loop that divides n1 (number of digits-1) times, and then with the remainder of the result of it, it will do % .
at this point you are left with some digit.
Then take n1 again, and divide it (number of digits-2) times, and then with the remainder of the result, it will do %.
at this point you are left with some another digit.
Compare the two digits. if first digit is smaller then the second digit, continue compairing digits by promotion of the digits location ( digitsNum--) .
do in loop steps 2-3-4.
if everything checks out, prints n1;
promote n1 (n1++), (up to n2)
loop everything again.
The problem is that with all the restricions on what I can use, I find my solution very hard to implement, and once I start, I just get one big mess .
Any suggestion on how can I improve it?
Hope it helps you.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
int num;;
int num2;
int flag=-1;
int i=0,j=0;
int rem,rem2;
printf("Enter First Number\n");
scanf("%d",&num);
printf("Enter Second Number\n");
scanf("%d",&num2);
if(num>num2)
{
printf("Wrong inputs have given\n");
exit(0);
}
int div=num2-num;
for(i=0;i<=div;i++)
{
num2=(num+i);
rem=(num2)%10;
num2/=10;
rem2=(num2)%10;
if(rem>rem2)
{
printf("....%d\n",num+i);
}
}
return 0;
}
Related
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;
}
Here is the code for "The Next Palindrome" which I wrote in C:
#include<stdio.h>
int main(void)
{
int check(int); //function declaration
int t,i,k[1000],flag,n;
scanf("%d",&t); //test cases
for(i=0; i<t; i++)
scanf("%d",&k[i]); //numbers
for(i=0; i<t; i++)
{
if(k[i]<=9999999) //Number should be of 1000000 digits
{
k[i]++;
while(1)
{
flag=check(k[i]); //palindrome check
if(flag==1)
{
printf("%d\n",k[i]); //prints if it is palindrome and breaks
break;
}
else
k[i]++; //go to the next number
}
}
}
return 0;
}
int check(int n)
{
int rn=0;
int temp=n;
while(n!=0)
{
rn=rn*10+n%10; //reversing
n=n/10;
}
if(rn==temp) //number is palindrome
return 1;
else //number is not a palindrome
return 0;
}
It is a beginner level problem from SPOJ.
I tried to run this code on Codeblocks and it ran fluently.
In SPOJ, why is it showing wrong output?
In SPOJ, why is it showing wrong output?
This is nice solution and it works for small inputs, however it will not pass SPOJ for several reasons.
The requirement is:
A positive integer is called a palindrome if its representation in the
decimal system is the same when read from left to right and from right
to left. For a given positive integer K of not more than 1000000
digits, write the value of the smallest palindrome larger than K to
output. Numbers are always displayed without leading zeros.
Input:
The first line contains integer t, the number of test cases.
Integers K are given in the next t lines.
So which requirements are broken in your program?
1) Your assumption is that only 1000 numbers will be given for processing since
you declared
k[1000]
wrong, the number of lines is given in first line. It could be much more than 1000. You have to dynamically assign the storage for the numbers.
2)
The line
if(k[i]<=9999999)
assumes that input is less than 9999999
- wrong, the requirement says positive integer K of not more than 1000000 digits which imply that much larger numbers e.g. 199999991 also have to be accepted.
3) The statement
For a given positive integer K of not more than 1000000 digits
as well as warning
Warning: large Input/Output data, be careful with certain languages
leads us to conclusion that really big numbers should be expected!
The int type is not a proper vehicle for storing such big numbers. The int will fail to hold the value if the number is bigger than INT_MAX +2147483647. (Check C Library <limits.h>)
So, how to pass SPOJ challange?
Hint:
One of the possible solutions - operate on strings.
// C program to print reverse of a number using for loop
#include<stdio.h>
int main()
{
long int num,i;
int d;
printf("\n enter number");
scanf("%ld",&num);
printf("\n the reverse of number %ld is ",num);
for(i=0;num>0;i++)
{
d=num%10;
num=num/10;
printf("%d",d);
}
return 0;
}
I think there is no terminating given in this code as the for loop will run infinte times, but this code is working fine, so can someone explain this code?
In order to understand the loop you need to understand the working of % 10 and /= 10 operations.
The first one, the remainder of division by ten, chops off the last decimal digit. The second one drops that digit from the number, because the division is done in integers.
Dividing a number by ten repeatedly will make it a zero aftre a number of iterations equal to the number of digits in the number, so that is when your loop is going to stop.
Problem : Consider the following algorithm to generate a sequence of
numbers. Start with an integer n. If n is even, divide by 2. If n is
odd, multiply by 3 and add 1. Repeat this process with the new value
of n, terminating when n = 1. The input will consist of a series of
pairs of integers i and j, one pair of integers perline. All integers
will be less than 1,000,000 and greater than 0.
For each pair of
input integers i and j, output i, j in the same order in which they
appeared in the input and then the maximum cycle length for integers
between and including i and j. These three numbers should be separated
by one space, with all three numbers on one line and with one line of
output for each line of input.
sample input :
1 10
sample output:
1 10 20
so i wrote this :
#include <stdio.h>
#include <string.h>
struct line{int in1;int in2;int result;};
int cycle(int in);
int main(int argc, char *argv[]) {
int cycle(int in);
char c;
int firstIn=0;
struct line l[500] ;
int pointer=0;
while(2<3){
l[pointer].in1=0;
l[pointer].in2=0;
scanf("%u %u",&l[pointer].in1,&l[pointer].in2);
if(l[pointer].in1<1||l[pointer].in2<1){
break;
}
int maxCyc=0;
int j,m;
int min,max;
if(l[pointer].in1>l[pointer].in2){
max=l[pointer].in1;
min=l[pointer].in2;
}
else{
max=l[pointer].in2;
min=l[pointer].in1;
}
for(j=min;j<=max;j++){
m = cycle(j);
if(m>maxCyc)
maxCyc=m;
}
l[pointer].result=maxCyc;
printf("%d %d %d\n",l[pointer].in1,l[pointer].in2,l[pointer].result);
pointer++;
}
}
int cycle(int in){
int cyc = 1;
while(in>1){
if(in%2==0){
cyc++;
in=in/2;
}
else{
cyc++;
in=in*3+1;
}
}
return cyc;
}
Its completly ok but when you change while(in>1) in cycle method to while(in!=1) it gets much more slower. my question is why?!
Time when its while(in>1) : 0.683 sec
and when its while(in!=1) : I waited more than 5 min nothing
happened yet :)
for input : 1 1000000
there is no infinite loop or something because in cant get below 1 at all(for that it must be already 1) .
Best regards
When you call cycle with the input value 113383, the process eventually sets n to
827370449, and 3*827370449+1 is 2482111348, which is greater than the maximum signed int and is interpreted as -1812855948. So there's your first negative number where there should be no negative number.
If this process then eventually sets n to -2, it will loop infinitely between -2 and -1 from then on. There may be other loops I haven't considered.
If you were to use an unsigned int, there is a possibility (I haven't checked) that this too will overflow eventually, which will not result in a negative value but will result in an incorrect value, invalidating your results.
No matter what integer representation you use, it would probably be a good idea to compare n with (maximum-1)/3 at the top of each loop, where maximum is the largest possible positive value of your integer type, just to be sure you do not overflow.
As you told me it was a simple overflow problem thx everyone.
max int value is 2,147,483,647; So when i changed int cycle(int in) to int cycle(long long int in) my problem was solved.
i also figured it out that my first answer with while(in>1) was wrong.
When an integer overflow occurs,the value will go below 0 .That was the reason while(in!=1) was an infinte loop.
I was really tired that i didn't figure it out by myself. sorry for that :)
Create a program to find out the first perfect square greater than 1 that occurs in the Fibonacci sequence and display it to the console.
I have no output when I enter an input.
#include <stdio.h>
#include <math.h>
int PerfectSquare(int n);
int Fibonacci(int n);
main()
{
int i;
int number=0;
int fibNumber=0;
int psNumber=0;
printf("Enter fibonacci number:");
scanf("%i",&number);
fibNumber = Fibonacci(number);
psNumber = PerfectSquare(fibNumber);
if(psNumber != 0){
printf("%i\n",psNumber);
}
}
int PerfectSquare(int n)
{
float root = sqrt(n);
if (n == ((int) root)*((int) root))
return root;
else
return 0;
}
int Fibonacci(int n){
if (n==0) return 0;
if (n==1) return 1;
return( Fibonacci(n-1)+Fibonacci(n-2) );
}
Luke is right. If your input is n, then the Fibonacci(n) returns the (n+1)th Fibonacci number.
Your program check whether (number +1)th is perfect square or not actually.
If you enter 12, then there is output. Because the 13th Fibonacci number is 144. And it is perfect square. PS: print fibNumber instead of psNumber.
printf("%i\n", fibNumber);
Right now you're only calculating one Fibonacci number and then testing whether it's a perfect square. To do this correctly you'll have to use a loop.
First suggestion is to get rid of the recursion to create fib numbers. You can use 2 variables and continually track the last 2 fib numbers. They get added something like:
fib1=0;fib2=1;
for(i=3;i<MAXTOCHECK;i++)
{
if(fib1<fib2)
fib1+=fib2;
else
fib2+=fib1;
}
What is nice about this method is that first you can change you seeds to anything you want. This is nice to find fib like sequences. For example Lucas numbers are seeded with 2 and 1. Second, you can put your check for square inline and not completely recalculate the sequence each time.
NOTE: As previously mentioned, your index may be off. There is some arbitrariness of indexing fib numbers from how it is initially seeded. This can seen if you reseed with 1 and 1. You get the same sequence shifted by 1 index. So be sure that you use a consistent definition for indexing the sequence.