Submission #131113

#	Time	Username	Problem	Language	Result	Execution time	Memory
131113		BThero	Ljetopica (COI19_ljetopica)	C++17	25 / 100	91 ms	31992 KiB

ljetopica

// Why am I so dumb? :c
// chrono::system_clock::now().time_since_epoch().count()

//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>

#define pb push_back
#define mp make_pair

#define all(x) (x).begin(), (x).end()

#define fi first
#define se second

using namespace std;
using namespace __gnu_pbds;

typedef long long ll;   
typedef pair<int, int> pii;
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

const int MAXN = (int)1e3 + 5;
const int MOD = (int)1e9 + 7;

int cnt[2][2][MAXN][MAXN];

int sum[2][2][MAXN][MAXN];

string s, A, B;

int pw[MAXN];

int n, k;

int addMod(int a, int b, int m = MOD) {
    a += b;

    if (m <= a) {
        a -= m;
    }

    return a;
}

int mulMod(int a, int b, int m = MOD) {
    return a * 1ll * b % m;
}

void pre() {
    pw[0] = 1;

    for (int i = 1; i < MAXN; ++i) {
        pw[i] = addMod(pw[i - 1], pw[i - 1]);
    }
}

void upd(int &a, int b) {
    a = addMod(a, b);
}

int L(int fl, int le, int pos, int u) {
    return mulMod(sum[fl][le][pos][u], 2);
}

int R(int fl, int le, int pos, int u) {
    return addMod(L(fl, le, pos, u), cnt[fl][le][pos][u]);
}

void calc(string t) {
    for (int i = 0; i <= n; ++i) {
        for (int j = 0; j <= n; ++j) {
            for (int fl = 0; fl < 2; ++fl) {
                for (int le = 0; le < 2; ++le) {
                    cnt[fl][le][i][j] = 0;
                    sum[fl][le][i][j] = 0;
                }
            }
        }
    }

    if (t[0] == '0') {
        return;
    }

    cnt[0][0][0][0] = 1;
    sum[0][0][0][0] = 1;
    cnt[1][0][0][0] = 1;
    sum[1][0][0][0] = 1;

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j <= k; ++j) {
            // less = 1

            upd(cnt[0][1][i + 1][j], cnt[0][1][i][j]);
            upd(cnt[1][1][i + 1][j], cnt[1][1][i][j]);
            upd(cnt[1][1][i + 1][j + 1], cnt[0][1][i][j]);
            upd(cnt[0][1][i + 1][j + 1], cnt[1][1][i][j]);

            // less = 0

            if (s[i + 1] == 'L') {
                if (t[i + 1] == '0') {
                    upd(cnt[0][0][i + 1][j], cnt[0][0][i][j]);
                    upd(cnt[0][0][i + 1][j + 1], cnt[1][0][i][j]);
                }
                else {
                    upd(cnt[0][1][i + 1][j], cnt[0][0][i][j]);
                    upd(cnt[0][1][i + 1][j + 1], cnt[1][0][i][j]);
                    upd(cnt[1][0][i + 1][j], cnt[1][0][i][j]);
                    upd(cnt[1][0][i + 1][j + 1], cnt[0][0][i][j]);
                }
            }
            else {
                if (t[i + 1] == '0') {
                    upd(cnt[1][0][i + 1][j], cnt[1][0][i][j]);
                    upd(cnt[1][0][i + 1][j + 1], cnt[0][0][i][j]);
                }
                else {
                    upd(cnt[0][0][i + 1][j], cnt[0][0][i][j]);
                    upd(cnt[0][0][i + 1][j + 1], cnt[1][0][i][j]);
                    upd(cnt[1][1][i + 1][j], cnt[1][0][i][j]);
                    upd(cnt[1][1][i + 1][j + 1], cnt[0][0][i][j]);
                }
            }
        }
    }

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j <= k; ++j) {
            if (s[i + 1] == 'L') {
                upd(sum[0][1][i + 1][j], L(0, 1, i, j));
                upd(sum[0][1][i + 1][j + 1], L(1, 1, i, j));
                upd(sum[1][1][i + 1][j + 1], R(0, 1, i, j));
                upd(sum[1][1][i + 1][j], R(1, 1, i, j));

                if (t[i + 1] == '0') {
                    upd(sum[0][0][i + 1][j], L(0, 0, i, j));
                    upd(sum[0][0][i + 1][j + 1], L(1, 0, i, j));
                }
                else {
                    upd(sum[0][1][i + 1][j], L(0, 0, i, j));
                    upd(sum[0][1][i + 1][j + 1], L(1, 0, i, j));
                    upd(sum[1][0][i + 1][j], R(1, 0, i, j));
                    upd(sum[1][0][i + 1][j + 1], R(0, 0, i, j));
                }
            }
            else {
                upd(sum[0][1][i + 1][j], R(0, 1, i, j));
                upd(sum[0][1][i + 1][j + 1], R(1, 1, i, j));
                upd(sum[1][1][i + 1][j + 1], L(0, 1, i, j));
                upd(sum[1][1][i + 1][j], L(1, 1, i, j));

                if (t[i + 1] == '0') {
                    upd(sum[1][0][i + 1][j], L(1, 0, i, j));
                    upd(sum[1][0][i + 1][j + 1], L(0, 0, i, j));
                }
                else {
                    upd(sum[0][0][i + 1][j], R(0, 0, i, j));
                    upd(sum[0][0][i + 1][j + 1], R(1, 0, i, j));
                    upd(sum[1][1][i + 1][j], L(1, 0, i, j));
                    upd(sum[1][1][i + 1][j + 1], L(0, 0, i, j));
                }
            }
        }
    }
}

void solve() {
    scanf("%d %d", &n, &k);
    cin >> s >> A >> B;
    s = '#' + s;
    
    {
        reverse(all(A));
        int p = 0;

        while (A[p] == '0') {
            ++p;
        }

        A[p] = '0';

        for (int i = 0; i < p; ++i) {
            A[p] = '1';
        }

        reverse(all(A));
    }

    int ans = 0;

    calc(B);
    ans = addMod(ans, sum[0][0][n - 1][k]);
    ans = addMod(ans, sum[0][1][n - 1][k]);
    ans = addMod(ans, sum[1][0][n - 1][k]);
    ans = addMod(ans, sum[1][1][n - 1][k]);
    calc(A);
    ans = addMod(ans, MOD - sum[0][1][n - 1][k]);
    ans = addMod(ans, MOD - sum[1][1][n - 1][k]);

    printf("%d\n", ans);
}

int main() {
    #ifdef IOI
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    #endif

    int tt = 1;

    pre();

    while (tt--) {
        solve();
    }

    return 0;
}

Compilation message (stderr)

ljetopica.cpp: In function 'void solve()':
ljetopica.cpp:173:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &k);
     ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 0 / 14
• Subtask 3: 17 / 17
• Subtask 4: 0 / 61