add 1528 & 1579

1501-1600/1528_shuffle_string.rb

@@ -0,0 +1,6 @@
+# @param {String} s
+# @param {Integer[]} indices
+# @return {String}
+def restore_string(s, indices)
+ indices.zip(s.chars).sort_by(&:first).map(&:last).join
+end

1501-1600/1579_remove_max_number_of_edges_to_keep_graph_fully_traversable.rb

@@ -0,0 +1,50 @@
+class UnionFind
+ def initialize(n)
+ @linked = (0..n).to_a
+ end
+
+ def find(x)
+ @linked[x] = find(@linked[x]) if x != @linked[x]
+ @linked[x]
+ end
+
+ def union(x, y)
+ return if (x_set = find(x)) == (y_set = find(y))
+
+ @linked[x_set] = @linked[y_set]
+ end
+
+ def num_of_sets
+ @linked[1..].map { |x| find(x) }.tally.size
+ end
+end
+
+# @param {Integer} n
+# @param {Integer[][]} edges
+# @return {Integer}
+def max_num_edges_to_remove(n, edges)
+ adj = Array.new(3) { [] }
+ edges.each { |type, u, v|
+ adj[type-1] << [u, v]
+ }
+
+ removed_edges = 0
+ alice_uf = UnionFind.new(n)
+ bob_uf = UnionFind.new(n)
+
+ adj[2].each { |u, v|
+ a = alice_uf.union(u, v)
+ b = bob_uf.union(u, v)
+ removed_edges += 1 unless a && b
+ }
+
+ adj[1].each { |u, v|
+ removed_edges += 1 unless bob_uf.union(u, v)
+ }
+
+ adj[0].each { |u, v|
+ removed_edges += 1 unless alice_uf.union(u, v)
+ }
+
+ (alice_uf.num_of_sets == 1 && bob_uf.num_of_sets == 1) ? removed_edges : -1
+end