【題解】LeetCode 1411. Number of Ways to Paint N × 3 Grid

class Solution {
public:
    int numOfWays(int n) {
        long long dp[5005][2], p = 1e9+7;
        dp[1][0] = 6;
        dp[1][1] = 6;
        for (int i = 2; i <= n; i++){
            dp[i][0] = (dp[i-1][0]*3 + dp[i-1][1]*2) % p;
            dp[i][1] = (dp[i-1][0]*2 + dp[i-1][1]*2) % p;
            //cout << dp[i][0] << " " << dp[i][1] << "\n";
        }
        return (dp[n][0]+dp[n][1]) % p;
    }
};