ugly_no.py

#https://www.geeksforgeeks.org/ugly-numbers/
def getNthUglyNo(n): 
  
    ugly = [0] * n # To store ugly numbers 
  
    # 1 is the first ugly number 
    ugly[0] = 1
  
    # i2, i3, i5 will indicate indices for 2,3,5 respectively 
    i2 = i3 =i5 = 0
  
    # set initial multiple value 
    next_multiple_of_2 = 2
    next_multiple_of_3 = 3
    next_multiple_of_5 = 5
  
    # start loop to find value from ugly[1] to ugly[n] 
    for l in range(1, n): 
  
        # choose the min value of all available multiples 
        ugly[l] = min(next_multiple_of_2, next_multiple_of_3, next_multiple_of_5) 
  
        # increment the value of index accordingly 
        if ugly[l] == next_multiple_of_2: 
            i2 += 1
            next_multiple_of_2 = ugly[i2] * 2
           
  
        if ugly[l] == next_multiple_of_3: 
            i3 += 1
            next_multiple_of_3 = ugly[i3] * 3
            
  
        if ugly[l] == next_multiple_of_5:  
            i5 += 1
            next_multiple_of_5 = ugly[i5] * 5
            
  
    # return ugly[n] value 
    return ugly[-1] 
  
def main(): 
  
    n = 11
  
    print ("un is",getNthUglyNo(n) )
  
  
if __name__ == '__main__': 
    main()