Python: Find the indices for which the numbers in the list drops
Python Programming Puzzles: Exercise-23 with Solution
Write a Python program to find the indices for which the numbers in the list drops.
NOTE: You can detect multiple drops just by checking if nums[i] < nums[i-1].
Input: [0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0] Output: [1, 4, 6, 8, 10, 11, 15, 16, 18] Input: [6, 5, 4, 3, 2, 1] Output: [1, 2, 3, 4, 5] Input: [1, 19, 5, 15, 5, 25, 5] Output: [2, 4, 6]
Sample Solution-1:
Python Code:
#License: https://bit.ly/3oLErEI
def test(nums):
drop_indices = []
for i in range(1, len(nums)):
if nums[i] < nums[i - 1]:
drop_indices.append(i)
return drop_indices
nums = [0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0]
print("Original list:")
print(nums)
print("Indices for which the numbers of the said list drops.:")
print(test(nums))
nums = [6,5,4,3,2,1]
print("\nOriginal list:")
print(nums)
print("Indices for which the numbers of the said list drops.:")
print(test(nums))
nums = [1,19,5,15,5,25,5]
print("\nOriginal list:")
print(nums)
print("Indices for which the numbers of the said list drops.:")
print(test(nums))
Sample Output:
Original list: [0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0] Indices for which the numbers of the said list drops.: [1, 4, 6, 8, 10, 11, 15, 16, 18] Original list: [6, 5, 4, 3, 2, 1] Indices for which the numbers of the said list drops.: [1, 2, 3, 4, 5] Original list: [1, 19, 5, 15, 5, 25, 5] Indices for which the numbers of the said list drops.: [2, 4, 6]
Flowchart:
Visualize Python code execution:
The following tool visualize what the computer is doing step-by-step as it executes the said program:
Sample Solution-2:
Python Code:
#License: https://bit.ly/3oLErEI
def test(nums):
return [i for i in range(1, len(nums)) if nums[i] < nums[i - 1]]
nums = [0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0]
print("Original list:")
print(nums)
print("Indices for which the numbers of the said list drops.:")
print(test(nums))
nums = [6,5,4,3,2,1]
print("\nOriginal list:")
print(nums)
print("Indices for which the numbers of the said list drops.:")
print(test(nums))
nums = [1,19,5,15,5,25,5]
print("\nOriginal list:")
print(nums)
print("Indices for which the numbers of the said list drops.:")
print(test(nums))
Sample Output:
Original list: [0, -1, 3, 8, 5, 9, 8, 14, 2, 4, 3, -10, 10, 17, 41, 22, -4, -4, -15, 0] Indices for which the numbers of the said list drops.: [1, 4, 6, 8, 10, 11, 15, 16, 18] Original list: [6, 5, 4, 3, 2, 1] Indices for which the numbers of the said list drops.: [1, 2, 3, 4, 5] Original list: [1, 19, 5, 15, 5, 25, 5] Indices for which the numbers of the said list drops.: [2, 4, 6]
Flowchart:
Visualize Python code execution:
The following tool visualize what the computer is doing step-by-step as it executes the said program:
Python Code Editor :
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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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