2192

2101-2200/2192_all_ancestors_of_a_node_in_a_directed_acyclic_graph.rb

@@ -0,0 +1,24 @@
+# @param {Integer} n
+# @param {Integer[][]} edges
+# @return {Integer[][]}
+def get_ancestors(n, edges)
+ ancestors = Array.new(n) { [] }
+ edges.each do |k, v|
+ ancestors[v] << k
+ end
+
+ ancestors.map do |a|
+ t = []
+ visited = {}
+ queue = a.clone
+ until queue.empty?
+ x = queue.shift
+ next if visited.has_key?(x)
+
+ visited[x] = true
+ t << x
+ queue += ancestors[x]
+ end
+ t.uniq.sort
+ end
+end