2026-01-03 13:57:12 +0300 MSK

Number of Ways to Paint N × 3 Grid
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Code

class Solution:
    def numOfWays(self, n: int) -> int:
        MOD = 10**9 + 7
        A = B = 6

        for _ in range(2, n + 1):
            A, B = (2*A + 2*B) % MOD, (2*A + 3*B) % MOD

        return (A + B) % MOD