Submission #234216

#	Time	Username	Problem	Language	Result	Execution time	Memory
234216		kartel	Ljetopica (COI19_ljetopica)	C++14	8 / 100	84 ms	16128 KiB

ljetopica

#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
#define in(x) freopen(x, "r", stdin)
#define out(x) freopen(x, "w", stdout)
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-O3")
#define F first
#define S second
#define pb push_back
#define N +1005
#define MaxS N * N
#define M ll(1e9 + 7)
#define sz(x) (int)x.size()
#define re return
#define oo ll(1e18)
#define el '\n'
#define pii pair <int, int>
using namespace std;
//using namespace __gnu_pbds;
//typedef tree <int, null_type, less_equal <int> , rb_tree_tag, tree_order_statistics_node_update> ordered_set;
typedef long long ll;
typedef long double ld;

ll f[N][N][2] {0};
int lss, len, n, i, z, k;

ll sm(ll x, ll y) {return (x + y) % M;}
ll mult(ll x, ll y) {return (x * y) % M;}

ll bp(ll x, ll y)
{
    if (y == 0) return 1ll;
    if (y % 2) return mult(bp(x, y - 1), x);

    ll a = bp(x, y / 2);

    return mult(a, a);
}

string dec(string x)
{
    int i = n - 1;
    while (i >= 0 && x[i] == '0') x[i] = '1', i--;

    x[i] = '0';

    return x;
}

ll calc(string x, string y)
{
    memset(f, 0, sizeof(f));

    f[1][0][0] = bp(2, n - 1);

    for (len = 1; len < n; len++)
    for (z = 0; z <= k; z++)
    for (lss = 0; lss < 2; lss++)
    {
        if (f[len][z][lss] == 0) continue;
        if (!lss)
        {
            if (x[len] == y[len])
            {
                if (x[len] == '1')
                {
                    f[len + 1][z][lss] = sm(f[len + 1][z][lss], bp(2, n - len - 1));
                    f[len + 1][z + 1][1] = sm(f[len + 1][z + 1][1], f[len][z][lss]);
                }
                f[len + 1][z][lss] = sm(f[len + 1][z][lss], f[len][z][lss]);
            }
            else if (x[len] < y[len])
            {
                f[len + 1][z + 1][lss] = sm(f[len + 1][z + 1][lss], sm(bp(2, n - len - 1), f[len][z][lss]));
                f[len + 1][z][1] = sm(f[len + 1][z][1], f[len][z][lss]);
            }
            else f[len + 1][z + 1][lss] = sm(f[len + 1][z + 1][lss], f[len][z][lss]);
        }
        else
        {
            if (x[len] == '0')
            {
                f[len + 1][z][lss] = sm(f[len + 1][z][lss], f[len][z][lss]);
                f[len + 1][z + 1][lss] = sm(f[len + 1][z + 1][lss], sm(f[len][z][lss], bp(2, n - len - 1)));
            }
            else
            {
                f[len + 1][z + 1][lss] = sm(f[len + 1][z + 1][lss], f[len][z][lss]);
                f[len + 1][z][lss] = sm(f[len + 1][z][lss], sm(f[len][z][lss], bp(2, n - len - 1)));
            }
        }
    }

    return sm(f[n][k][0], f[n][k][1]);
}

int main()
{
    srand(time(0));
    ios_base::sync_with_stdio(0);
    iostream::sync_with_stdio(0);
    ios::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);

//    in("input.txt");
//    out("output.txt");

    string x, l, r, s;
    cin >> n >> k;

    cin >> s;
    cin >> l;
    cin >> r;

    x = "1";
    for (i = 0; i < n - 1; i++) if (s[i] == 'L') x += "0"; else x += "1";

    ll cur1 = calc(x, r);
    ll cur2 = calc(x, dec(l));

    x = "1";
    for (i = 0; i < n - 1; i++) if (s[i] == 'R') x += "0"; else x += "1";

    cur1 = sm(cur1, calc(x, r));
    cur2 = sm(cur2, calc(x, dec(l)));

//    cout << cur2 << el;

    cout << (cur1 - cur2 + M) % M;
}

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