You're given a graph; your goal is to add edges to it so that every node has an even degree. Find the minimum number of edges to add to achieve this.

Find the longest path in a tree where no two adjacent nodes on the path have the same character. The tree is defined by parent-child relationships and each node has an associated character.

You are given a grid of numbers. Find the maximum possible score by traversing the grid, starting from the top-left cell and ending at the bottom-right cell, following specific movement rules.