#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct Node node;
struct Node {
  int vertex;
  struct Node *next;
};

typedef struct List list;
struct List {
  node *head;
  node *tail;
};

typedef struct Graph graph;
struct Graph {
  int nvertices;
  int *visited;
  list *vertices;
};

graph *init_graph(int n) {
  graph *graph = malloc(sizeof(struct Graph));

  graph->nvertices = n;
  graph->vertices = malloc(n * sizeof(struct List));
  graph->visited = malloc(n * sizeof(int));

  memset(graph->visited, 0, sizeof(int) * n);

  return graph;
}

void insert(list *list, int vertex) {
  node *new = malloc(sizeof(struct Node));
  new->next = NULL;
  new->vertex = vertex;

  if (!list->head)
    list->head = list->tail = new;
  else
    list->tail->next = new, list->tail = new;
}

void pop(list *list) {
  if (!list->head)
    return;

  node *next = list->head->next;
  free(list->head);

  if (!next)
    list->tail = next;
  list->head = next;
}

void add_edge(graph *graph, int src, int dst) {
  insert(&graph->vertices[src], dst);
  insert(&graph->vertices[dst], src);
}

void dfs(struct Graph *graph, int vertex) {
  list list = graph->vertices[vertex];

  printf("%d ", vertex);
  graph->visited[vertex] = 1;

  node *cur = list.head;

  while (cur) {
    if (!graph->visited[cur->vertex])
      dfs(graph, cur->vertex);

    cur = cur->next;
  }
}

void bfs(struct Graph *graph, int _vertex) {
  list next;
  next.head = next.tail = NULL;

  graph->visited[_vertex] = 1;
  insert(&next, _vertex);

  while (next.head) {
    int vertex = next.head->vertex;
    list list = graph->vertices[vertex];
    node *cur = list.head;

    printf("%d ", vertex);
    pop(&next);

    while (cur) {
      if (!graph->visited[cur->vertex]) {
        graph->visited[cur->vertex] = 1;
        insert(&next, cur->vertex);
      }

      cur = cur->next;
    }
  }
}

int main() {
  const int ROOT = 0;
  const int SIZE = 5;

  struct Graph *graph = init_graph(SIZE);
  add_edge(graph, 0, 1);
  add_edge(graph, 0, 3);
  add_edge(graph, 0, 4);
  add_edge(graph, 2, 3);
  add_edge(graph, 1, 3);

  printf("DFS: ");
  dfs(graph, ROOT);
  printf("\n");

  memset(graph->visited, 0, sizeof(int) * graph->nvertices);

  printf("BFS: ");
  bfs(graph, ROOT);
  printf("\n");

  // free
  for (int i = 0; i < graph->nvertices; i++)
    while(graph->vertices[i].head)
      pop(&graph->vertices[i]);
  free(graph->visited);
  free(graph->vertices);
  free(graph);

  return 0;
}