------
## 最终结论
```python
import re

def is_valid_URL(url):
    pattern = re.compile(r'^(https?://)(www\.)?([a-zA-Z0-9-]+)(\.[a-zA-Z]{2,})(/.*)?$')
    return bool(pattern.match(url))

# Test cases
assert is_valid_URL("https://www.google.com") == True
assert is_valid_URL("https:/www.gmail.com") == False
assert is_valid_URL("https:// www.redit.com") == False
```