hdoj_5642 (动规---------他们说这题思想是数位dp，然而我看了一天半数位dp还是没弄懂。。。)

#include<iostream>#include<cstring>#include<cstdio>#define LL long long #define MOD 1000000007using namespace std;const int maxn = 2000+10;int N;LL p[maxn][5];int main() {int T; cin >> T;while(T--) {memset(p, 0, sizeof(p));scanf("%d", &N); p[1][1] = 26; p[1][2] = 0; p[1][3] = 0;for(int i = 2; i <= N; i++) {p[i][1] = 25*(p[i-1][1]+p[i-1][2]+p[i-1][3])%MOD;p[i][2] = p[i-1][1];p[i][3] = p[i-1][2];}cout << (p[N][1]+p[N][2]+p[N][3])%MOD << endl;//这个cout输出也要记得取模！！！ }return 0;}