[parkhojeong] WEEK 08 Solutions

clone-graph/parkhojeong.py

@@ -0,0 +1,31 @@
+"""
+# Definition for a Node.
+class Node:
+    def __init__(self, val = 0, neighbors = None):
+        self.val = val
+        self.neighbors = neighbors if neighbors is not None else []
+"""
+
+from typing import Optional
+class Solution:
+    def cloneGraph(self, node: Optional['Node']) -> Optional['Node']:
+
+        visited = {}
+
+        def deep_copy(node):
+            if node is None:
+                return None
+
+            cur = Node(node.val)
+            visited[node.val] = cur
+
+            cur.val = node.val
+            for neighbor in node.neighbors:
+                if neighbor.val in visited:
+                    cur.neighbors.append(visited[neighbor.val])
+                else:
+                    cur.neighbors.append(deep_copy(neighbor))
+
+            return cur
+
+        return deep_copy(node)

longest-repeating-character-replacement/parkhojeong.py

@@ -0,0 +1,25 @@
+class Solution:
+    def characterReplacement(self, s: str, k: int) -> int:
+        freq = [0] * 26
+        max_len = 0
+
+        def idx(ch):
+            return ord(ch) - ord('A')
+
+        left = 0
+        for i in range(len(s)):
+            freq[idx(s[i])] += 1
+            window_size = i - left + 1
+            size = window_size - max(freq)
+
+            while size > k:
+                freq[idx(s[left])] -= 1
+
+                left += 1
+                window_size -= 1
+                size = window_size - max(freq)
+
+            max_len = max(max_len, window_size)
+
+        return max_len
+

palindromic-substrings/parkhojeong.py

@@ -0,0 +1,15 @@
+class Solution:
+    def countSubstrings(self, s: str) -> int:
+        s_len = len(s)
+        success = set([(i, i + 1) for i in range(s_len)])
+
+        for r in range(s_len):
+            for l in range(0, r):
+                if r - l == 1 and s[l] == s[r]:
+                    success.add((l, r + 1))
+                    continue
+
+                if (l + 1, r) in success and s[l] == s[r]:
+                    success.add((l, r + 1))
+
+        return len(success)

reverse-bits/parkhojeong.py

@@ -0,0 +1,9 @@
+class Solution:
+    def reverseBits(self, n: int) -> int:
+        m = 0
+        for i in range(32):
+            remainder = n % 2
+            n = n // 2
+            m += pow(2, 31 - i) * remainder
+
+        return m