24.md

Min between two given nodes of binary tree

void buildGraph(Node* root, unordered_map<int, vector<int>>& adj) {
        if(root == NULL) {
            return;
        }
        
        if(root->left) {
            adj[root->data].push_back(root->left->data);
            adj[root->left->data].push_back(root->data);
        }
        
        if(root->right) {
            adj[root->data].push_back(root->right->data);
            adj[root->right->data].push_back(root->data);
        }
        
        buildGraph(root->left, adj);
        buildGraph(root->right, adj);
    }
    
    int findDist(Node* root, int a, int b) {
        // Build Graph 
        unordered_map<int, vector<int>> adj;
        buildGraph(root, adj);
        
        // Perform BFS 
        queue<int> q;
        unordered_set<int> st;
        
        q.push(a);
        st.insert(a);
        
        int cnt = 0;
        
        while(!q.empty()) {
            int sz = q.size();
            for(int i = 0; i < sz; i++) {
                int curr = q.front();
                q.pop();
                
                if(curr == b) {
                    return cnt;
                }
                
                for(auto it : adj[curr]) {
                    if(st.find(it) == st.end()) {
                        q.push(it);
                        st.insert(it); 
                    }
                }
            }
            cnt++;
        }
        
        return -1;
    }