Sliding window max (peeked a bit)

leetcode/stuff.py

@@ -1,4 +1,6 @@
 import copy
+import itertools
+import math
 import random
 import typing
 
@@ -538,19 +540,31 @@ def copy_random_list(
 
 
 def sum_max_sub_array(nums: list[int]) -> int:
-    window_size: int = 1
-    begin: int = 0
-    end: int = window_size
-    max_sum: int = sum(nums)
+    mmax = last = prev = nums[0]
 
-    while end - begin <= len(nums):
-        while end <= len(nums):
-            max_sum = max(max_sum, sum(nums[begin:end]))
-            begin += 1
-            end += 1
+    for i in range(1, len(nums)):
+        prev = nums[i] + last
+        last = max(nums[i], prev)
+        mmax = max(mmax, last)
 
-        window_size += 1
-        begin = 0
-        end = window_size
+    return mmax
 
-    return max_sum
+
+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