Ugly Number Problem

Problem:

The problem of ugly number is a common DP problem.

Description:

Ugly numbers are positive numbers whose prime factors only include 2,3,5,7. For example, 6,8 are ugly while 14 is not ugly since it includes another prime factor 7.Note that 1 is typically treated as an ugly number. courtesy: leetcode.com

#include <stdio.h>
#include <iostream>

using namespace std;

int _min(int a,int b,int c)
{
	if(a<=b && a<=c)
	{
		return a;
	}
	if(b<=a && b<=c)
	{
		return b;
	}
	if(c<=b && c<=a)
	{
		return c;
	}
}

int main()
{
	int two_used=0,three_used=0,five_used=0;
	int next_ugly_number;
	int a,b,c;
	int ugly[155];
	
	ugly[0]=1;
	
	for(int i=1;i<155;i++)
	{
		a = ugly[two_used]*2;
		b = ugly[three_used]*3;
		c = ugly[five_used]*5;
		
		next_ugly_number = _min(a,b,c);
		ugly[i]=next_ugly_number;
		if(next_ugly_number==a)
		two_used++;
		if(next_ugly_number==b)
		three_used++;
		if(next_ugly_number==c)
		five_used++;
	}
	//cout<<_min(5,2,3)<<endl;
	int t,n;
	scanf("%d",&t);
	while(t--)
	{
		scanf("%d",&n);
		cout<<ugly[n-1]<<endl;
	}
	return 0;
}