Euler 070 partial replacement of numpy loops. (#9055)

* Euler 070 partial replacement of numpy loops.

* Update project_euler/problem_070/sol1.py

* project_euler.yml: Upgrade actions/checkout@v4 and add numpy

* Update project_euler.yml

---------

Co-authored-by: Christian Clauss <cclauss@me.com>

.github/workflows/project_euler.yml

@@ -14,26 +14,26 @@ jobs:
   project-euler:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-python@v4
         with:
           python-version: 3.x
       - name: Install pytest and pytest-cov
         run: |
           python -m pip install --upgrade pip
-          python -m pip install --upgrade pytest pytest-cov
+          python -m pip install --upgrade numpy pytest pytest-cov
       - run: pytest --doctest-modules --cov-report=term-missing:skip-covered --cov=project_euler/ project_euler/
   validate-solutions:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-python@v4
         with:
           python-version: 3.x
       - name: Install pytest and requests
         run: |
           python -m pip install --upgrade pip
-          python -m pip install --upgrade pytest requests
+          python -m pip install --upgrade numpy pytest requests
       - run: pytest scripts/validate_solutions.py
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

project_euler/problem_070/sol1.py

@@ -30,6 +30,8 @@ https://en.wikipedia.org/wiki/Euler's_totient_function#Euler's_product_formula
 """
 from __future__ import annotations
 
+import numpy as np
+
 
 def get_totients(max_one: int) -> list[int]:
     """
@@ -42,17 +44,14 @@ def get_totients(max_one: int) -> list[int]:
     >>> get_totients(10)
     [0, 1, 1, 2, 2, 4, 2, 6, 4, 6]
     """
-    totients = [0] * max_one
-
-    for i in range(max_one):
-        totients[i] = i
+    totients = np.arange(max_one)
 
     for i in range(2, max_one):
         if totients[i] == i:
-            for j in range(i, max_one, i):
-                totients[j] -= totients[j] // i
+            x = np.arange(i, max_one, i)  # array of indexes to select
+            totients[x] -= totients[x] // i
 
-    return totients
+    return totients.tolist()
 
 
 def has_same_digits(num1: int, num2: int) -> bool: