1#include <iostream>2#include <string>3using namespace std;4 5const int P = 998244353, N = 1e4 + 10, M = 20;6int n, m;7string s;8int dp[1 << M];9 10int solve() {11    dp[0] = 1;12    for (int i = 0; i < n; ++i) {13        for (int j = (1 << (m - 1)) - 1; j >= 0; --j) {14            int k = (j << 1) | (s[i] - '0');15            if (j != 0 || s[i] == '1')16                dp[k] = (dp[k] + dp[j]) % P;17        }18    }19    int ans = 0;20    for (int i = 0; i < (1 << m); ++i) {21        ans = (ans + 1ll * i * dp[i]) % P;22    }23    return ans;24}25 26int solve2() {27    int ans = 0;28    for (int i = 0; i < (1 << n); ++i) {29        int cnt = 0;30        int num = 0;31        for (int j = 0; j < n; ++j) {32            if (i & (1 << j)) {33                num = num * 2 + (s[j] - '0');34                cnt++;35            }36        }37        if (cnt <= m) (ans += num) %= P;38    }39    return ans;40}41 42int main() {43    cin >> n >> m;44    cin >> s;45    if (n <= 20) {46        cout << solve2() << endl;47    }48    cout << solve() << endl;49    return 0;50}51 

假设输入的 $s$ 是包含 $n$ 个字符的 $01$ 串，完成下面的判断题和单选题。