[radiantchoi] WEEK 10 Solutions

course-schedule/radiantchoi.py

@@ -0,0 +1,25 @@
+from collections import deque, defaultdict
+
+class Solution:
+    def canFinish(self, numCourses: int, prerequisites: List[List[int]]) -> bool:
+        posts = defaultdict(list)
+        indegree = [0] * numCourses
+
+        for prerequisite in prerequisites:
+            posts[prerequisite[1]].append(prerequisite[0])
+            indegree[prerequisite[0]] += 1
+
+        completed = 0
+        q = deque(list(filter(lambda x: indegree[x] == 0, range(numCourses))))
+
+        while q:
+            current = q.popleft()
+            completed += 1
+
+            for post in posts[current]:
+                indegree[post] -= 1
+
+                if indegree[post] == 0:
+                    q.append(post)
+
+        return completed == numCourses

invert-binary-tree/radiantchoi.ts

@@ -0,0 +1,28 @@
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+
+function invertTree(root: TreeNode | null): TreeNode | null {
+  if (root === null) {
+    return null;
+  }
+
+  const temp = root.left;
+  root.left = root.right;
+  root.right = temp;
+
+  invertTree(root.left);
+  invertTree(root.right);
+
+  return root;
+}

jump-game/radiantchoi.py

@@ -0,0 +1,11 @@
+class Solution:
+    def canJump(self, nums: List[int]) -> bool:
+        reachable = [False] * len(nums)
+        destination = len(nums) - 1
+
+        for index, strength in list(enumerate(nums))[::-1]:
+            if index + strength >= destination:
+                reachable[index] = True
+                destination = index
+
+        return reachable[0]