516. Leaf Node Value Sum

Given a binary tree represented as an adjacency list, calculate the sum of all values belonging to 'leaf' nodes. A leaf node is defined as a node that has no outgoing edges to children. The tree is directed from parent to child. You are provided with a dictionary tree where keys are node IDs (integers) and values are lists of child node IDs, and a dictionary values where keys are node IDs and values are their corresponding integer values.

Example:
Input: tree = {0: [1, 2], 1: [], 2: []}, values = {0: 10, 1: 5, 2: 7}
Output: 12

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