bool printCommonAncestor(struct node* node,int x,int y) { if (node == NULL) return false; // first recur on left subtree bool left = printCommonAncestor(node->left,x,y); bool right = printCommonAncestor(node->right,x,y); if(left && right) printf("%d ", node->data); if(left || right) { if(node->data == x || node->data==y) { printf("%d ", node->data); } return true; } if(node->data == x || node->data==y) return true; return false; // now deal with the node } Do a Post order traversal. If its on left and right of the tree then return that node

Array of 256 chars for each string. Assign to 0. Then as a character comes increment the count. Compute a hash key using these 256 values and store the hash key->String mapping. Do so for each string, if the mapping already exists, add this string to the list of strings for this mapping.