Create 1411-number-of-ways-to-paint-n-3-grid.js

Author: everthis

1411-number-of-ways-to-paint-n-3-grid.js

@@ -0,0 +1,18 @@
+/**
+ * @param {number} n
+ * @return {number}
+ */
+const numOfWays = function (n) {
+  let a121 = 6,
+    a123 = 6,
+    b121,
+    b123,
+    mod = 1e9 + 7
+  for (let i = 1; i < n; ++i) {
+    b121 = a121 * 3 + a123 * 2
+    b123 = a121 * 2 + a123 * 2
+    a121 = b121 % mod
+    a123 = b123 % mod
+  }
+  return (a121 + a123) % mod
+}