Submission #140509

#	Time	Username	Problem	Language	Result	Execution time	Memory
140509		wasyl	Snake Escaping (JOI18_snake_escaping)	C++11	75 / 100	2009 ms	44644 KiB

snake_escaping

#include <bits/stdc++.h>
using namespace std;

constexpr int lax = 20, qax = 1e6, nax = (1 << lax);

int l, q, n, tab[nax], pre[3][nax];
string s;
vector< int > ind;

int id(const char c)
{
    if (c == '?') return 2;
    return c - '0';
}

int rek(const int t, string& s, const int v, const int msk = 0)
{
    for (int j = v; j < ind.size(); ++j)
    {
        int i = ind[j];
        if (id(s[i]) == t)
        {
            int res = 0;
            if (t == 2)
            {
                s[i] = '0';
                res += rek(t, s, j + 1, msk);
                s[i] = '1';
                res += rek(t, s, j + 1, msk + (1 << i));
                s[i] = '?';
                return res;
            }
            if (t == 0)
            {
                s[i] = '?';
                res += rek(t, s, j + 1, msk + (1 << i));
                s[i] = '1';
                res -= rek(t, s, j + 1, msk);
                s[i] = '0';
                return res;
            }
            if (t == 1)
            {
                s[i] = '?';
                res += rek(t, s, j + 1, msk + (1 << i));
                s[i] = '0';
                res -= rek(t, s, j + 1, msk);
                s[i] = '1';
                return res;
            }

        }
    }
    return pre[t][msk]; //spo
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> l >> q;
    n = (1 << l);

    cin >> s;

    for (int i = 0; i < n; ++i)
        tab[i] = s[i] - '0';

    for (int i = 0; i < n; ++i)
        pre[0][i] = tab[(n - 1) - i];
    for (int i = 0; i < n; ++i)
        pre[1][i] = tab[i];
    for (int i = 0; i < n; ++i)
        pre[2][i] = tab[i];

    for (int i = 0; i < l; ++i)
        for (int j = 0; j < n; ++j)
            if ((1 << i) & j)
                pre[0][j] += pre[0][j - (1 << i)],
                pre[1][j] += pre[1][j - (1 << i)];

                for (int i = 0; i < q; ++i)
                {
                    string s; cin >> s;
                    reverse(begin(s), end(s));
                    int zl[2] = {0, 0};
                    for (char c : s)
                        if (c == '0' or c == '1')
                            ++zl[c - '0'];
                    if (zl[0] <= lax / 3)
                    {
                        ind.clear();
                        for (int i = 0; i < l; ++i)
                            if (s[i] == '0')
                                ind.push_back(i);
                        int msk = 0;
                        for (int i = 0; i < l; ++i)
                            if (s[i] == '?')
                                msk += (1 << i);
                        cout << rek(0, s, 0, msk) << '\n';
                    }
                    else if (zl[1] <= lax / 3)
                    {
                        ind.clear();
                        for (int i = 0; i < l; ++i)
                            if (s[i] == '1')
                                ind.push_back(i);
                        int msk = 0;
                        for (int i = 0; i < l; ++i)
                            if (s[i] == '?')
                                msk += (1 << i);
                        cout << rek(1, s, 0, msk) << '\n';
                    }
                    else if (l - zl[0] - zl[1] <= lax / 3)
                    {
                        ind.clear();
                        for (int i = 0; i < l; ++i)
                            if (s[i] == '?')
                                ind.push_back(i);
                        int msk = 0;
                        for (int i = 0; i < l; ++i)
                            if (s[i] == '1')
                                msk += (1 << i);
                        cout << rek(2, s, 0, msk) << '\n';
                    }
                }
}

Compilation message (stderr)

snake_escaping.cpp: In function 'int rek(int, std::__cxx11::string&, int, int)':
snake_escaping.cpp:18:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int j = v; j < ind.size(); ++j)
                     ~~^~~~~~~~~~~~
snake_escaping.cpp: In function 'int main()':
snake_escaping.cpp:79:13: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
             if ((1 << i) & j)
             ^~
snake_escaping.cpp:83:17: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
                 for (int i = 0; i < q; ++i)
                 ^~~

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 10 / 10
• Subtask 4: 53 / 53
• Subtask 5: 0 / 25