出现MLE百思不得其解

#include <bits/stdc++.h>
using namespace std;
string str("#"), p[205];
int l, ans, pi[205][15], f[205][200005], dp[200005];

int main() {
    ios::sync_with_stdio(false);
    cout.tie(0), cin.tie(0);
    do {
        cin >> p[++l];
        p[l] = "#" + p[l];
    } while (p[l][1] != '.');
    string s;
    while (cin >> s && s.length())
        str = str + s;
    for (int i = 1; i < l; ++i) {
        for (int j = 2, k = 0; j < p[i].length(); ++j) {
            while (k != 0 && p[i][k+1] != p[i][j]) k = pi[i][k];
            if (p[i][k+1] == p[i][j]) ++k;
            pi[i][j] = k;
        }
    }
    for (int i = 1; i < l; ++i) {
        for (int j = 1, k = 0; j < str.length(); ++j) {
            while (k != 0 && p[i][k+1] != str[j]) k = pi[i][k];
            if (p[i][k+1] == str[j]) ++k;
            f[i][j] = k;
        }
    }
    dp[0] = 1;
    for (int i = 1; i < str.length(); ++i) {
        for (int j = 1; j < l; ++j) {
            int len = p[j].length() - 1;
            if (i >= len && f[j][i] == len)
                dp[i] |= dp[i - len];
        }
    }
    for (int i = 1; i < str.length(); ++i)
        if (dp[i]) ans = i;
    cout << ans;
    return 0;
}

for (; cin >> p[l] && p[l][0] != '.'; ++l)
  p[l] = "#" + p[l];
for (string s; cin >> s; str += s);