재밌는 계단수들

zeta_python/completed/1562.py

@@ -0,0 +1,17 @@
+N = int(input())
+
+D = [[0] * (1 << 10) for _ in range(10)]
+
+for i in range(1, 10):
+    D[i][1 << i] = 1
+
+for i in range(0, N - 1):
+    Dn = [[0] * (1 << 10) for _ in range(10)]
+    for n in range(10):
+        for m in range(1024):
+            if n < 9:
+                Dn[n][m | (1 << n)] += D[n + 1][m] % 1000000000
+            if n > 0:
+                Dn[n][m | (1 << n)] += D[n - 1][m] % 1000000000
+    D = Dn
+print(sum([D[i][1023] for i in range(10)]) % 1000000000)