2466

Author: theforestvn88

2401-2500/2466_count_ways_to_build_good_strings.rb

@@ -0,0 +1,16 @@
+# @param {Integer} low
+# @param {Integer} high
+# @param {Integer} zero
+# @param {Integer} one
+# @return {Integer}
+def count_good_strings(low, high, zero, one)
+    mod = 1000000007
+    dp = Array.new(high + 1, 0)
+    dp[0] = 1
+    (1..high).each { |i|
+        dp[i] = (dp[i] + dp[i - zero]) % mod if i - zero >= 0
+        dp[i] = (dp[i] + dp[i - one]) % mod if i - one >= 0
+    }
+
+    dp[low..high].sum % mod
+end