[8804who] WEEK 03 solutions

combination-sum/8804who.py

@@ -0,0 +1,22 @@
+class Solution:
+    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
+        dp = {}
+
+        for i in range(target+1):
+            dp[i] = set()
+
+        for candidate in candidates:
+            if candidate <= target:
+                dp[candidate].add(tuple([candidate]))
+
+        for i in range(target+1):
+            for candidate in candidates:
+                if i-candidate >= 0:
+                    for j in dp[i-candidate]:
+                        arr = [nums for nums in j]+[candidate]
+                        arr.sort()
+                        dp[i].add(tuple(arr))
+
+        answer = [list(nums) for nums in dp[target]]
+        return answer
+

decode-ways/8804who.py

@@ -0,0 +1,23 @@
+class Solution:
+    def numDecodings(self, s: str) -> int:
+        dp = [0]*(len(s)+1)
+        s = '0'+s
+        dp[0] = 1
+        for i in range(1, len(s)):
+            if int(s[i]) == 0:
+                if int(s[i-1]) != 1 and int(s[i-1]) != 2:
+                    return 0 
+                else:
+                    dp[i]=dp[i-2]
+            elif int(s[i]) <= 6:
+                if int(s[i-1]) != 1 and int(s[i-1]) != 2:
+                    dp[i]=dp[i-1]
+                else:
+                    dp[i]=dp[i-1]+dp[i-2]
+            else:
+                if int(s[i-1]) == 1:
+                    dp[i]=dp[i-1]+dp[i-2]
+                else:
+                    dp[i]=dp[i-1]
+        return dp[-1]
+

maximum-subarray/8804who.py

@@ -0,0 +1,14 @@
+class Solution:
+    def maxSubArray(self, nums: List[int]) -> int:
+        s = 0
+        min_s = 0
+        max_s = nums[0]
+
+        for num in nums:
+            s += num
+            if max_s < s-min_s:
+                max_s=s-min_s
+            if min_s > s:
+                min_s = s
+        return max_s
+

number-of-1-bits/8804who.py

@@ -0,0 +1,5 @@
+class Solution:
+    hammingWeight = lambda _, n: n.bit_count()
+
+
+

valid-palindrome/8804who.py

@@ -0,0 +1,6 @@
+import re
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        parsed_string = re.sub('[^a-zA-Z0-9]','',s).upper()
+        return parsed_string == parsed_string[::-1]
+