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-rw-r--r--Year_1/Programming_2/data_structures/dfs.cc191
1 files changed, 191 insertions, 0 deletions
diff --git a/Year_1/Programming_2/data_structures/dfs.cc b/Year_1/Programming_2/data_structures/dfs.cc
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+#include<iostream>
+#include<vector>
+#include<queue>
+#define W -1
+#define G 0
+#define B 1
+
+using namespace std;
+
+template<class H>
+class node {
+public:
+ explicit node(H key, node<H>* next) : _key{key}, _next(next) {}
+ const H& key() const { return _key; }
+ H& key() { return _key; }
+ const node<H>*& next() const { return _next; }
+ node<H>*& next() { return _next; }
+private:
+ H _key;
+ node<H>* _next;
+};
+
+template<class H>
+class list {
+public:
+ list() : _head{nullptr} {}
+ ~list() {
+ while(_head) {
+ auto tmp = _head;
+ _head = _head->next();
+ delete tmp;
+ }
+ }
+ list<H>* push(H val) {
+ auto iter = _head;
+ while(iter && iter->next())
+ iter = iter->next();
+
+ if(!iter)
+ _head = new node<H>{val, nullptr};
+ else
+ iter->next() = new node<H>{val, nullptr};
+
+ return this;
+ }
+ void print() {
+ auto iter = _head;
+ while(iter) {
+ cout << iter->key() << ' ';
+ iter = iter->next();
+ }
+ }
+ vector<H> as_vector() {
+ vector<H> v;
+ auto iter = _head;
+ while(iter) {
+ v.push_back(iter->key());
+ iter = iter->next();
+ }
+ return v;
+ }
+ node<H>* search(H val) {
+ auto iter = _head;
+ while(iter && iter->key() != val) {
+ iter = iter->next();
+ }
+
+ return iter;
+ }
+private:
+ node<H>* _head;
+};
+
+template<class H>
+class graph {
+private:
+ int _len, _nodes, _edges;
+ int* _parents;
+ int* _radixes;
+ int* _distances;
+ int* _finishes;
+ int* _colors;
+ int _time;
+ int _current;
+ H** _k; // it works like a dictionary, it saves the keys
+ list<int>** _adj;
+ int _index(H val) {
+ for(int i = 0; i < _nodes; ++i)
+ if(*_k[i] == val) return i;
+
+ return -1;
+ }
+ void _dfsvisit(int u) {
+ _colors[u] = G;
+ _distances[u] = _time++;
+ _radixes[u] = _current;
+ for(auto const& v : _adj[u]->as_vector()) {
+ if(_colors[v] == W) {
+ _parents[v] = u;
+ _dfsvisit(v);
+ }
+ }
+ _colors[u] = B;
+ _finishes[u] = _time++;
+ }
+public:
+ graph(int len) : _len{len}, _nodes{0}, _edges{0} {
+ _k = new H*[len];
+ _adj = new list<int>*[_len];
+ _parents = new int[_len];
+ _radixes = new int[_len];
+ _distances = new int[_len];
+ _finishes = new int[_len];
+ _colors = new int[_len];
+ for(int i = 0; i < _len; ++i) {
+ _k[i] = nullptr;
+ _adj[i] = new list<int>{};
+ }
+ }
+
+ graph<H>* add_node(H k) {
+ if(_nodes == _len) return this;
+ if(_index(k) >= 0) return this; // node is already there
+
+ _k[_nodes++] = new H(k);
+
+ return this;
+ }
+
+
+ void dfs() {
+ _time = 0;
+ for(int i = 0; i < _nodes; ++i) {
+ _colors[i] = W;
+ _parents[i] = -1;
+ }
+
+ for(int i = 0; i < _nodes; ++i) {
+ if(_colors[i] == W) {
+ _current = i;
+ _dfsvisit(i);
+ }
+ }
+ for(int i = 0; i < _nodes; ++i) {
+ cout << *_k[i] << "(" << _distances[i]+1 << ',' << _finishes[i]+1 << ")" << endl;
+ }
+ }
+
+ graph<H>* add_edge(H x, H y) {
+ int i = _index(x);
+ int j = _index(y);
+ if(i < 0 || j < 0) return this;
+
+ if(!_adj[i]->search(j)) {
+ _adj[i]->push(j);
+ _edges++;
+ }
+
+ return this;
+ }
+
+ void print() {
+ for(int i = 0; i < _nodes; ++i) {
+ cout << "(" << i << ", " << *_k[i] << "): ";
+ for(auto const& j : _adj[i]->as_vector())
+ cout << "(" << j << ", " << *_k[j] << "), ";
+ cout << '\n';
+ }
+ }
+};
+
+
+int main() {
+ graph<char>* g = new graph<char>(6);
+ g->add_node('u')->add_node('v')->add_node('x')->add_node('y');
+ g->add_node('w')->add_node('z');
+ g->add_edge('u', 'v');
+ g->add_edge('u', 'x');
+ g->add_edge('x', 'v');
+ g->add_edge('y', 'x');
+ g->add_edge('v', 'y');
+ g->add_edge('w', 'y');
+ g->add_edge('w', 'z');
+ g->add_edge('z', 'z');
+
+ g->print();
+ g->dfs();
+
+ delete g;
+ return 0;
+}