add combination sum, maximum subarray solution

Author: i-mprovising

combination-sum/i-mprovising.py

@@ -0,0 +1,19 @@
+"""
+Time complexity O(c*t)
+Space complexity O(c*t)
+
+Dynamic programming
+"""
+
+class Solution:
+    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
+        # init dp array
+        dp = [[] for _ in range(target+1)] # dp[i] : combinations to sum to i
+        dp[0] = [[]]
+
+        for candidate in candidates:
+            for num in range(candidate, target+1):
+                for comb in dp[num-candidate]:
+                    dp[num].append(comb + [candidate])
+        
+        return dp[-1]

maximum-subarray/i-mprovising.py

@@ -0,0 +1,18 @@
+"""
+Time complexity O(n)
+Space complexity O(n)
+
+Dynamic programming
+"""
+
+
+class Solution:
+    def maxSubArray(self, nums: List[int]) -> int:
+        n = len(nums)
+        dp = [0 for _ in range(n)]
+        dp[0] = nums[0]
+
+        for i in range(1, n):
+            dp[i] = max(dp[i-1]+nums[i], nums[i])
+        
+        return max(dp)