136 - Ugly Numbers

 Ugly Numbers 

Ugly numbers are numbers whose only prime factors are 2, 3 or 5. The sequence

1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, ...

shows the first 11 ugly numbers. By convention, 1 is included.

Write a program to find and print the 1500'th ugly number.

Input and Output
There is noinput to this program. Output should consist of a single line asshown below, with <number> replaced by the number computed.

Sample output
The 1500'th ugly number is <number>.

[cpp]
#include<stdio.h>  
int main(void) 
{ 
    int un[1505]={0}; 
    int m2=0,m3=0,m5=0,i,t; 
    un[0]=1; 
    for(i=1;i<1500;i++) 
    { 
        if(2*un[m2]>3*un[m3]) 
            t=un[m3]*3; 
        else 
            t=un[m2]*2; 
        if(t>un[m5]*5) 
            t=un[m5]*5; 
 
        if(t == 2*un[m2]) m2++; 
        if(t == 3*un[m3]) m3++; 
        if(t == 5*un[m5]) m5++; 
 
        un[i]=t; 
    } 
    printf("The 1500'th ugly number is %d.\n",un[1499]); 
    return 0; 
}