void tree_dfs(Node node, int mode)
{
/**
* Printeaza arborele in functie de mod:
* 0 - preordine
* 1 - inordine
* 2 - postordine
*/
if (!node)
return;
if (mode == 0)
printf("%c ", node->key);
tree_dfs(node->left, mode);
if (mode == 1)
printf("%c ", node->key);
tree_dfs(node->right, mode);
if (mode == 2)
printf("%c ", node->key);
}
/*
* Checks if the given decomposition constitutes a tree using DFS
*/
bool is_tree() {
if ((num_vertices > 0) && num_vertices - 1 != num_edges) {
return false;
} else if (num_vertices == 0) {
return (num_edges == 0);
}
std::vector<int> seen(num_vertices, 0);
unsigned seen_size = 0;
bool cycle = !tree_dfs(seen,0,-1,seen_size);
if (cycle || seen_size != num_vertices) {
return false;
}
return true;
}
/*
* Helper method for is_tree(); not to be called from outside of the class
*/
bool tree_dfs(std::vector<int>& seen, unsigned root, unsigned parent, unsigned& num_seen) {
if (seen[root] != 0) {
return false;
}
seen[root] = 1;
num_seen++;
for (auto it = adj_list[root].begin(); it != adj_list[root].end(); it++) {
if (*it != parent) {
if (!tree_dfs(seen, *it, root,num_seen)) {
return false;
}
}
}
return true;
}
