lc1740

class Solution {
public:
    int findDistance(TreeNode* root, int p, int q) {
        TreeNode* theNode = lca(root,p,q);
        int left = findDist(theNode,p,0);
        int right = findDist(theNode,q,0);
        return left + right;
    }
    
    int findDist(TreeNode* parent, int target,int dist) {
        if(parent==NULL)
            return 0;
        if(parent->val==target)
            return dist;
        int left = findDist(parent->left,target,1+dist);
        int right = findDist(parent->right,target,1+dist);
        
        return max(left,right);
    }
    

    TreeNode* lca(TreeNode*root, int p, int q) {
        if(!root) {
            return NULL;
        }
        
        if(root->val == p || root->val ==q) {
            return root;
        }
        
        TreeNode* left = lca(root->left,p,q);
        TreeNode* right =lca(root->right, p ,q);
        
        if(left && right) {
            return root;
        }
        
        if(left) {
            return left;
        }
        if(right) {
            return right;
        }
        return NULL;
    }
    
};