Merge pull request neetcode-gh#1928 from saip7795/sp/min-window-substring

Create: 0076-min-window-substring.rb

Author: tahsintunan

ruby/0076-min-window-substring.rb

@@ -0,0 +1,41 @@
+
+def min_window(s, t)
+     
+    return "" if t == ""
+    count_t = Hash.new(0)
+    window = Hash.new(0)
+
+    t.each_char do |c|
+        count_t[c] +=1
+    end
+
+    have = 0
+    need = count_t.length
+
+    res = [-1,-1]
+    result_length = 9999999999
+    l = 0
+    (0..s.length-1).each do |r|
+        c = s[r]
+        window[c] +=1
+
+        have +=1 if ((count_t.keys.include?(c)) && (window[c] == count_t[c])) 
+        while(have == need)
+            if (r-l+1) < result_length
+                res = [l,r]
+                result_length = (r-l+1)
+
+            end
+            window[s[l]] -=1
+            have -=1 if ((count_t.keys.include?(s[l])) && (window[s[l]] < count_t[s[l]]))
+            l +=1
+        end
+    end
+    l = res[0]
+    r = res[1]
+    if result_length != 9999999999
+        return s[l..r]
+    else
+        return ""
+    end
+end