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Python: nth Hamming number

Python Itertools: Exercise-26 with Solution

Write a Python program to find the nth Hamming number. Use the itertools module.

Hamming numbers are numbers of the form
H = 2i x 3j x 5k Where i, j, k ≥ 0
The sequence of Hamming numbers 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 24, 25, 27. . . consists of all numbers of the form 2i.3j.5k where i, j and k are non-negative integers.

Sample Solution:

Python Code:

``````import itertools
from heapq import merge

def nth_hamming_number(n):
def num_recur():
last = 1
yield last
x, y, z = itertools.tee(num_recur(), 3)
for n in merge((2 * i for i in x), (3 * i for i in y), (5 * i for i in z)):
if n != last:
yield n
last = n
result =  itertools.islice(num_recur(), n)
return list(result)[-1]

print(nth_hamming_number(8))
print(nth_hamming_number(14))
print(nth_hamming_number(17))
```
```

Sample Output:

```9
20
27
```

Python Code Editor:

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Python: Tips of the Day

Inverts a dictionary with non-unique hashable values:

Example:

```def tips_collect_dictionary(obj):
inv_obj = {}
for key, value in obj.items():
inv_obj.setdefault(value, list()).append(key)
return inv_obj
ages = {
"Owen": 25,
"Jhon": 25,
"Pepe": 15,
}
print(tips_collect_dictionary(ages))
```

Output:

```{25: ['Owen', 'Jhon'], 15: ['Pepe']}
```

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