Create ugly_numbers.py

Author: abhisheks008

Dynamic Programming/Ugly Numbers/ugly_numbers.py

@@ -0,0 +1,79 @@
+# Python program to find n'th Ugly number
+# Method : Dynamic Programming
+# Abhishek Sharma. 2021
+
+# Problem Statement : Ugly numbers are numbers whose 
+#                     only prime factors are 2, 3 or 5.
+#                     Find out the nth Ugly number, where n is
+#                     given as the input to the program.
+
+# -----------------------------------------------------------------    
+
+# Function to get the nth ugly number 
+ 
+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):
+ 
+        # Shoose 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]
+ 
+# Driver Code
+if __name__ == '__main__':
+    print ("- Finding out n'th Ugly Number using Dynamic Method -")
+    print ("-----------------------------------------------------")
+    n = int(input("Enter any number : "))
+    print ()
+    print ("********************************************")
+    print ("The desired Ugly number is : ",getNthUglyNo(n))
+    
+    
+    
+# -----------------------------------------------------------------   
+# Input given :
+# - Finding out n'th Ugly Number using Dynamic Method -
+# -----------------------------------------------------
+# Enter any number : 150
+
+# -----------------------------------------------------
+# Output :
+# The desired Ugly number is :  5832
+
+# -----------------------------------------------------------------   
+
+# Code contributed by, Abhishek Sharma, 2021