Python: Find the three elements that sum to zero from a set of n real numbers
Python Class: Exercise-6 with Solution
Write a Python class to find the three elements that sum to zero from a set (array) of n real numbers.
Sample Solution:
Python Code:
class py_solution:
def threeSum(self, nums):
nums, result, i = sorted(nums), [], 0
while i < len(nums) - 2:
j, k = i + 1, len(nums) - 1
while j < k:
if nums[i] + nums[j] + nums[k] < 0:
j += 1
elif nums[i] + nums[j] + nums[k] > 0:
k -= 1
else:
result.append([nums[i], nums[j], nums[k]])
j, k = j + 1, k - 1
while j < k and nums[j] == nums[j - 1]:
j += 1
while j < k and nums[k] == nums[k + 1]:
k -= 1
i += 1
while i < len(nums) - 2 and nums[i] == nums[i - 1]:
i += 1
return result
print(py_solution().threeSum([-25, -10, -7, -3, 2, 4, 8, 10]))
Sample Output:
[[-10, 2, 8], [-7, -3, 10]]
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Previous: Write a Python class to find a pair of elements (indices of the two numbers) from a given array whose sum equals a specific target number.
Next: Write a Python class to implement pow(x, n).
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Python: Tips of the Day
Find current directory and file's directory:
To get the full path to the directory a Python file is contained in, write this in that file:
import os dir_path = os.path.dirname(os.path.realpath(__file__))
(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)
To get the current working directory use
import os cwd = os.getcwd()
Documentation references for the modules, constants and functions used above:
- The os and os.path modules.
- The __file__ constant
- os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
- os.path.dirname(path) (returns "the directory name of pathname path")
- os.getcwd() (returns "a string representing the current working directory")
- os.chdir(path) ("change the current working directory to path")
Ref: https://bit.ly/3fy0R6m
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