[Feat] Add more implementation on DP

Author: AustinPardosi

152-MaximumProductSubarray.py

@@ -0,0 +1,15 @@
+class Solution:
+    def maxProduct(self, nums: List[int]) -> int:
+        res = max(nums)
+        curMin, curMax = 1, 1
+
+        for num in nums:
+            if num == 0:
+                curMin, curMax = 1, 1
+                continue
+            temp = num * curMax
+            curMax = max(num * curMax, num * curMin, num)
+            curMin = min(temp, num * curMin, num)
+            res = max(curMax, res)
+
+        return res

202-HappyNumber.py

@@ -0,0 +1,19 @@
+class Solution:
+    def isHappy(self, n: int) -> bool:
+        history = set()
+        check = 0
+        tempStr = str(n)
+
+        while (check != 1) :
+            temp = 0
+            for i in tempStr:
+                temp += (int(i)**2)
+            check = temp
+            tempStr = str(check)
+
+            if (check in history) :
+                return False
+            else:
+                history.add(check)
+
+        return True

213-HouseRobberII.py

@@ -0,0 +1,16 @@
+class Solution:
+    def help(self, nums: List[int]) -> int:
+        rob1, rob2 = 0, 0
+
+        # rob1, rob2, n, n+1
+        for n in nums:
+            temp = max(rob1 + n, rob2)
+            rob1 = rob2
+            rob2 = temp
+
+        return rob2
+
+    def rob(self, nums: List[int]) -> int:
+        if len(nums) == 1:
+            return nums[0]
+        return max(self.help(nums[1:]), self.help(nums[:-1]))

322-CoinChange.py

@@ -0,0 +1,16 @@
+class Solution:
+    def coinChange(self, coins: List[int], amount: int) -> int:
+        # Dynamic Programming
+        # isi data semaksimal mungkin, karna kita bakal pilih minimum
+        dp = [amount + 1] * (amount + 1)
+        dp[0] = 0
+
+        for i in range(1, amount + 1):
+            for coin in coins:
+                if amount - coin >= 0:
+                    dp[i] = min(dp[i], 1 + dp[i - coin])
+
+        if dp[amount] == amount + 1:
+            return -1
+        else:
+            return dp[amount]

5-LongestPalindromicSubstring.py

@@ -0,0 +1,24 @@
+class Solution:
+    def longestPalindrome(self, s: str) -> str:
+        res = ""
+        resLen = 0
+
+        for i in range(len(s)):
+            # Odd
+            l, r = i, i
+            while (l >= 0 and r <= len(s) - 1) and (s[l] == s[r]):
+                if r - l + 1 > resLen:
+                    res = s[l : r + 1]
+                    resLen = r - l + 1
+                l -= 1
+                r += 1
+
+            # Even
+            l, r = i, i + 1
+            while (l >= 0 and r <= len(s) - 1) and (s[l] == s[r]):
+                if r - l + 1 > resLen:
+                    res = s[l : r + 1]
+                    resLen = r - l + 1
+                l -= 1
+                r += 1
+        return res

647-PalindromicSubstrings.py

@@ -0,0 +1,19 @@
+class Solution:
+    def countSubstrings(self, s: str) -> int:
+        res = 0
+
+        for i in range(len(s)):
+            # Odd
+            l, r = i, i
+            while (l >= 0 and r <= len(s) - 1) and (s[l] == s[r]):
+                res += 1
+                l -= 1
+                r += 1
+
+            # Even
+            l, r = i, i + 1
+            while (l >= 0 and r <= len(s) - 1) and (s[l] == s[r]):
+                res += 1
+                l -= 1
+                r += 1
+        return res

91-DecodeWays.py

@@ -0,0 +1,21 @@
+class Solution:
+    def numDecodings(self, s: str) -> int:
+        # in case string kosong return 1
+        history = {len(s): 1}
+
+        def dfs(i):
+            if i in history:
+                return history[i]
+            if s[i] == "0":
+                return 0
+
+            res = dfs(i + 1)
+            if i + 1 < len(s) and (
+                s[i] == "1" or (s[i] == "2" and s[i + 1] in "0123456")
+            ):
+                res += dfs(i + 2)
+
+            history[i] = res
+            return res
+
+        return dfs(0)