feat: DCC 23-02-2025 added.

Author: cvalingam

solutions/2889. Reshape Data Pivot/2889.py

@@ -0,0 +1,9 @@
+import pandas as pd
+
+def pivotTable(weather: pd.DataFrame) -> pd.DataFrame:
+    return weather.pivot_table(
+      index='month',
+      columns='city',
+      values='temperature',
+      aggfunc='max',
+    )

solutions/889. Construct Binary Tree from Preorder and Postorder Traversal/889.cs

@@ -0,0 +1,46 @@
+public class TreeNode
+{
+    public int val;
+    public TreeNode left;
+    public TreeNode right;
+    public TreeNode(int val = 0, TreeNode left = null, TreeNode right = null)
+    {
+        this.val = val;
+        this.left = left;
+        this.right = right;
+    }
+}
+
+public class Solution
+{
+    public TreeNode ConstructFromPrePost(int[] preorder, int[] postorder)
+    {
+        Dictionary<int, int> postToIndex = new Dictionary<int, int>();
+
+        for (int i = 0; i < postorder.Length; ++i)
+            postToIndex[postorder[i]] = i;
+
+        return Build(preorder, 0, preorder.Length - 1, postorder, 0, postorder.Length - 1, postToIndex);
+    }
+
+    private TreeNode Build(int[] pre, int preStart, int preEnd, int[] post, int postStart,
+                           int postEnd, Dictionary<int, int> postToIndex)
+    {
+        if (preStart > preEnd)
+            return null;
+        if (preStart == preEnd)
+            return new TreeNode(pre[preStart]);
+
+        int rootVal = pre[preStart];
+        int leftRootVal = pre[preStart + 1];
+        int leftRootPostIndex = postToIndex[leftRootVal];
+        int leftSize = leftRootPostIndex - postStart + 1;
+
+        TreeNode root = new TreeNode(rootVal);
+        root.left = Build(pre, preStart + 1, preStart + leftSize, post, postStart, leftRootPostIndex,
+                          postToIndex);
+        root.right = Build(pre, preStart + leftSize + 1, preEnd, post, leftRootPostIndex + 1,
+                           postEnd - 1, postToIndex);
+        return root;
+    }
+}