CS153/hw6/hw5programs/sp22_tests/dijkstras.oat

struct Graph {
  AdjList?[] adj_lists
}

struct AdjList {
  Edge[] edges
}

struct Edge {
  int neighbor;
  int weight
}

global e01 = new Edge { neighbor = 1; weight = 4 };
global e07 = new Edge { neighbor = 7; weight = 8 };

global e12 = new Edge { neighbor = 2; weight = 8 };
global e17 = new Edge { neighbor = 7; weight = 11 };

global e23 = new Edge { neighbor = 3; weight = 7 };
global e25 = new Edge { neighbor = 5; weight = 4 };
global e28 = new Edge { neighbor = 8; weight = 2 };

global e34 = new Edge { neighbor = 4; weight = 9 };

global e53 = new Edge { neighbor = 3; weight = 14 };
global e54 = new Edge { neighbor = 4; weight = 10 };

global e65 = new Edge { neighbor = 5; weight = 2 };
global e68 = new Edge { neighbor = 8; weight = 6 };

global e76 = new Edge { neighbor = 6; weight = 1 };
global e78 = new Edge { neighbor = 8; weight = 7 };

void print_int_array(int[] arr) {
  for (var i = 0; i < length(arr); i = i + 1;) {
    print_int(arr[i]);
    print_string(" ");
  }
  return;
}

bool is_queue_empty(bool[] queued) {
  for (var i = 0; i < length(queued); i = i + 1;) {
    if (queued[i]) {
      return false;
    }
  }
  return true;
}

int get_min_dist_node(bool[] queued, int[] dist) {
  var curr_min = -1;
  var curr_min_node = 0;
  for (var i = 0; i < length(queued); i = i + 1;) {
    if (queued[i]) {
      var curr_dist = dist[i];
      if (curr_dist != -1 & (curr_dist < curr_min | curr_min == -1)) {
        curr_min = curr_dist;
        curr_min_node = i;
      }
    }
  }
  return curr_min_node;
}

int[] dijkstras(Graph graph, int source) {
  var n = length(graph.adj_lists);
  var dist = new int[n]{id -> -1};
  var queued = new bool[n]{id -> true};

  dist[source] = 0;

  while (!is_queue_empty(queued)) {
    var curr = get_min_dist_node(queued, dist);
    queued[curr] = false;

    if?(AdjList a = graph.adj_lists[curr]) {
      var a_edges = a.edges;
      for (var i = 0; i < length(a_edges); i = i + 1;) {
        var curr_edge = a_edges[i];
        var curr_neighbor = curr_edge.neighbor;
        var alt_dist = dist[curr] + curr_edge.weight;
        if (dist[curr_neighbor] == -1 | alt_dist < dist[curr_neighbor]) {
          dist[curr_neighbor] = alt_dist;
        }
      }
    }
  }

  return dist;
}

int program (int argc, string[] argv) {
  var a0 = new AdjList { edges = new Edge[]{e01, e07} };
  var a1 = new AdjList { edges = new Edge[]{e12, e17} };
  var a2 = new AdjList { edges = new Edge[]{e23, e25, e28} };
  var a3 = new AdjList { edges = new Edge[]{e34} };
  var a4 = AdjList null;
  var a5 = new AdjList { edges = new Edge[]{e53, e54} };
  var a6 = new AdjList { edges = new Edge[]{e65, e68} };
  var a7 = new AdjList { edges = new Edge[]{e76, e78} };
  var a8 = AdjList null;

  var graph = new Graph { adj_lists = new AdjList?[]{a0, a1, a2, a3, a4, a5, a6, a7, a8} };
  
  var result = dijkstras(graph, 0);
  print_int_array(result);

  return 0;
}