Function pow26

String Algorithms/Required Substring.cpp:12–21

ll ans, dp[maxM][maxN];

ll pow26(ll b){
    ll a = 26;
    ll res = 1;
    while(b){
        if(b&1) res = (res * a) % MOD;
        a = (a * a) % MOD;
        b >>= 1;
    }
    return res;
}

bool good(vector<char> pre, int k){
    int SZ = (int) pre.size();