One more thought about max sub-array

leetcode/pyproject.toml

@@ -13,27 +13,14 @@ keywords = []
 authors = [
   { name = "Dan Buch", email = "dan@meatballhat.com" },
 ]
-classifiers = [
+classifiers = []
-  "Development Status :: 4 - Beta",
-  "Programming Language :: Python",
-  "Programming Language :: Python :: 3.7",
-  "Programming Language :: Python :: 3.8",
-  "Programming Language :: Python :: 3.9",
-  "Programming Language :: Python :: 3.10",
-  "Programming Language :: Python :: 3.11",
-  "Programming Language :: Python :: Implementation :: CPython",
-  "Programming Language :: Python :: Implementation :: PyPy",
-]
 dependencies = [
   "ipython",
-  "ipdb"
+  "ipdb",
+  "matplotlib",
+  "numpy"
 ]
 
-[project.urls]
-Documentation = "https://github.com/unknown/leetcode#readme"
-Issues = "https://github.com/unknown/leetcode/issues"
-Source = "https://github.com/unknown/leetcode"
-
 [tool.hatch.envs.default]
 dependencies = [
   "coverage[toml]>=6.5",

leetcode/stuff.py

@@ -1,4 +1,6 @@
 import copy
+import itertools
+import math
 import random
 import typing
 
@@ -535,3 +537,47 @@ def copy_random_list(
             ordered_copy[i].random = ordered_copy[hash_idx[hash(entry.random)]]
 
     return ordered_copy[0]
+
+
+def sum_max_sub_array(nums: list[int]) -> int:
+    mmax = last = prev = nums[0]
+
+    for i in range(1, len(nums)):
+        prev = nums[i] + last
+        last = max(nums[i], prev)
+        mmax = max(mmax, last)
+
+    return mmax
+
+
+def sum_max_sub_array_i(nums: list[int]) -> tuple[int, int]:
+    mmax_i: int = 0
+    mmax = last = prev = nums[0]
+
+    for i in range(1, len(nums)):
+        prev = nums[i] + last
+        last = max(nums[i], prev)
+        mmax_i = i if last > mmax else mmax_i
+        mmax = max(mmax, last)
+
+    return mmax_i, mmax
+
+
+def sum_max_sub_array_accum(nums: list[int]) -> int:
+    accum: list[int] = [nums[0]]
+
+    for i in range(1, len(nums)):
+        prev: int = nums[i] + accum[-1]
+        accum.append(max(nums[i], prev))
+
+    return max(accum)
+
+
+def accum_sub_array_maxes(nums: list[int]) -> list[int]:
+    accum: list[int] = [nums[0]]
+
+    for i in range(1, len(nums)):
+        prev: int = nums[i] + accum[-1]
+        accum.append(max(nums[i], prev))
+
+    return accum

leetcode/test_stuff.py

@@ -1,3 +1,5 @@
+import json
+
 import pytest
 
 import stuff
@@ -444,3 +446,32 @@ def test_trie_busy():
     assert trie.startsWith("rent") is True
     assert trie.startsWith("beer") is True
     assert trie.startsWith("jam") is True
+
+
+@pytest.mark.parametrize(
+    ("nums", "expected"),
+    [
+        (
+            [-2, 1, -3, 4, -1, 2, 1, -5, 4],
+            6,
+        ),
+        (
+            [1],
+            1,
+        ),
+        (
+            [5, 4, -1, 7, 8],
+            23,
+        ),
+        (
+            [-2, 1],
+            1,
+        ),
+        (
+            json.load(open(".testdata/max_sub_array0.json")),
+            11081,
+        ),
+    ],
+)
+def test_max_sub_array(nums: list[int], expected: int):
+    assert stuff.sum_max_sub_array(nums) == expected