1944

1901-2000/1944_number_of_visible_people_in_a_queue.rb

@@ -0,0 +1,19 @@
+# @param {Integer[]} heights
+# @return {Integer[]}
+def can_see_persons_count(heights)
+ ans = Array.new(heights.size, 0)
+ stack = []
+ heights.each_with_index { |h, i|
+ while !stack.empty? && heights[stack.last] < h
+ # each of previous with height < h will see the i-th
+ ans[stack.pop] += 1
+ end
+
+ # the last will see the i-th
+ ans[stack.last] += 1 unless stack.empty?
+
+ stack.push(i)
+ }
+
+ ans
+end