CareerCup

Use DP.

void foo(int n)
{
        static int ind2,ind3,ind5;
        static int arr[30],depth;
        int num2,num3,num5,num,flag=0;
        if(n<=0) return;
        if(depth==0)
        {
                ind2=ind3=ind5=0;// i know this is redundant
                arr[depth++]=1;
        }
        num2=arr[ind2]*2;
        num3=arr[ind3]*3;
        num5=arr[ind5]*5;
 
        num=min(num2,min(num3,num5));
 
        if(num==num2)
        {
                ind2++;
                if(arr[depth-1]!=num2)
                {
                        flag=1;
                        printf("%d\n",arr[depth-1]);
                        arr[depth++]=num2;
                }
        }
        else if(num==num3)
        {
                ind3++;
                if(arr[depth-1]!=num3)
                {
                        flag=1;
                        printf("%d\n",arr[depth-1]);
                        arr[depth++]=num3;
                }
        }
        else
        {
                ind5++;
                if(arr[depth-1]!=num5)
                {
                        flag=1;
                        printf("%d\n",arr[depth-1]);
                        arr[depth++]=num5;
                }
        }
        if(flag)
                foo(n-1);
        else
                foo(n);
        
}

Complete working code: ideone.com/qz4Py

It prints first n ugly numbers.
Note: I have also considered 1 as part of the ugly number series.

int getKthMagicNumber (int k) {
  queue<int> q2, q3, q5 ;
  int val = 1, minVal ;

  if (k <= 0)
    return 0 ;
  q2.push (2) ;
  q3.push (3) ;
  q5.push (5) ;

  for ( --k ; k > 0 ; -- k ) {
    minVal = min (q2.front(), min (q3.front(), q5.front())) ;
    if ( minVal == q5.front() ) {
      q5.pop () ;
    } else {
      if ( minVal == q3.front() ) {
        q3.pop () ;
      } else {
        q2.pop () ;
        q2.push (minVal*2) ;
      }
      q3.push (minVal*3) ;
    }
    q5.push (minVal*5);
  }
  return minVal ;
}

Lookup some combination of "ugly numbers", "hamming numbers" and "dijkstra"

<?php
for($i=1;$i<n;$i++)
{
$temp=i;
while($i%2==0)
{
$temp=i/2;
if($temp==1)
break;
}
if($temp==1 || $temp%3==0 || $temp%5==0)
echo $i." ";
}
?>

Why is it called 'ugly numbers'

void foo(int n)
{
for (int i =0; i <=n ; i++)
{
int counter = 0;

if (i % 2 == 0)
{
++counter;
}
if ( i % 3 == 0)
{
++counter;
}
if (i % 5 == 0)
{
++counter;
}

if (counter >= 1)
{
if (i % 7 != 0)
printf("%d \n", i);
}

counter = 0;
}

}
int main()
{
int n;

scanf("%d",&n);

foo(n);

return 0;
}