Codeforces 441E Valera and Number dp

Valera and Number

It feels like a very long time. . 

dp [o] [i] [mask], which represents what the final mask 9 Yes.

If the mask == 0, a representation of o rounds, Which current probability lowbit this state.

If the mask! = 0, o represents conducted round the final mask 9 is, from a probability of 10 1 in this state the number of successive start.

 

From dp [o] [i] [0] + 1 when after such operation can discard i, since these successive 1 has no use, even behind all this not also added +1.

#include<bits/stdc++.h>
#define LL long long
#define LD long double
#define ull unsigned long long
#define fi first
#define se second
#define mk make_pair
#define PLL pair<LL, LL>
#define PLI pair<LL, int>
#define PII pair<int, int>
#define SZ(x) ((int)x.size())
#define ALL(x) (x).begin(), (x).end()
#define fio ios::sync_with_stdio(false); cin.tie(0);

using namespace std;

const int N = 250 + 7;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;
const double eps = 1e-10;
const double PI = acos(-1);

template<class T, class S> inline void add(T &a, S b) {a += b; if(a >= mod) a -= mod;}
template<class T, class S> inline void sub(T &a, S b) {a -= b; if(a < 0) a += mod;}
template<class T, class S> inline bool chkmax(T &a, S b) {return a < b ? a = b, true : false;}
template<class T, class S> inline bool chkmin(T &a, S b) {return a > b ? a = b, true : false;}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int x, k, p;
double dp[2][250][1 << 9];
double p1, p2;

double (*f)[1 << 9] = dp[0];
double (*g)[1 << 9] = dp[1];

inline int getLow(int mask) {
    for(int i = 0; ; i++) if(mask >> i & 1) return i;
}

int main() {
    scanf("%d%d%d", &x, &k, &p);
    p1 = 1.0 * p / 100;
    p2 = 1 - p1;

    int c = 0, mask = (x & 511);

    if(mask) {
        for(int i = 9; ; i++) {
            if(x >> i & 1) c++;
            else break;
        }
    } else {
        c = getLow(x);
    }

    f[c][mask] = 1;

    for(int o = 0; o < k; o++) {
        swap(f, g);
        for(int i = 0; i <= 240; i++)
            for(int mask = 0; mask < (1 << 9); mask++)
                f[i][mask] = 0;
        for(int i = 0; i < 240; i++) {
            for(int mask = 0; mask < (1 << 9); mask++) {
                if(mask) {
                    // +1
                    if(mask + 1 == (1 << 9)) {
                        f[i + 9][0] += g[i][mask] * p2;
                    } else {
                        f[i][mask + 1] += g[i][mask] * p2;
                    }

                    // *2

                    int nmask = (mask << 1) & 511;
                    int bit = mask >> 8 & 1;

                    if(nmask) {
                        if(bit) {
                            f[i + 1][nmask] += g[i][mask] * p1;
                        } else {
                            f[0][nmask] += g[i][mask] * p1;
                        }
                    } else {
                        f[9][0] += g[i][mask] * p1;
                    }

                } else {
                    // +1
                    f[0][1] += g[i][mask] * p2;
                    // *2
                    f[i + 1][0] += g[i][mask] * p1;
                }
            }
        }
    }

    double ans = 0;

    for(int i = 0; i <= 240; i++) {
        for(int mask = 0; mask < (1 << 9); mask++) {
            if(mask) {
                ans += getLow(mask) * f[i][mask];
            } else {
                ans += i * f[i][mask];
            }
        }
    }

    printf("%.12f\n", ans);
    return 0;
}

/*
*/