update

Author: tiationg-kho

[M]dynamic-programming/[M]dynamic-programming/410-split-array-largest-sum.py

@@ -6,42 +6,39 @@ def splitArray(self, nums: List[int], k: int) -> int:
         for i, num in enumerate(nums):
             total += num
             prefix[i + 1] = total
-        dp = [[float('inf')] * (k + 1) for _ in range(n)]
-        for i in range(n):
-            dp[i][1] = prefix[i + 1] - prefix[0]
 
+        dp = [[float('inf') for _ in range(k + 1)] for _ in range(n)]
+        for end in range(n):
+            dp[end][1] = prefix[end + 1] - prefix[0]
+
         for end in range(n):
             for interval in range(2, k + 1):
                 for cut in range(end, interval - 2, - 1):
-                    cur_res = max(dp[cut - 1][interval - 1], prefix[end + 1] - prefix[cut])
-                    dp[end][interval] = min(dp[end][interval], cur_res)
-        
+                    largest_sum = max(dp[cut - 1][interval - 1], prefix[end + 1] - prefix[cut])
+                    dp[end][interval] = min(dp[end][interval], largest_sum)
         return dp[n - 1][k]
 
-# time O(n** 2 * k)
+# time O(n**2 * k)
 # space O(nk)
 # using dynamic programming and interval (start from one interval)
 
 class Solution:
     def splitArray(self, nums: List[int], k: int) -> int:
 
-        def valid(limit):
+        def valid(bound):
+            group = 1
             total = 0
-            group = 0
             for num in nums:
-                if num > limit:
+                if num > bound:
                     return False
-                if total + num <= limit:
-                    total += num
-                else:
+                if total + num > bound:
                     group += 1
                     total = num
-            if total:
-                group += 1
+                else:
+                    total += num
             return group <= k
 
-        total = sum(nums)
-        left, right, boundary = 0, total, - 1
+        left, right, boundary = 0, sum(nums), - 1
         while left <= right:
             m = (left + right) // 2
             if valid(m):