题目链接
const int MAXN = 1100;int ipt[MAXN], dp[MAXN];int main(){// freopen("in.txt", "r", stdin); int n; while (~RI(n)) { CLR(dp, 0); FE(i, 1, n) RI(ipt[i]); FE(i, 1, n) { dp[i + 1] = (2 * dp[i] % MOD + MOD + 2 - dp[ipt[i]]) % MOD; } WI(dp[n + 1]); } return 0;}
