【Codeforces441E】Valera and Number [DP]

Valera and Number

Time Limit: 20 Sec  Memory Limit: 512 MB

Description

　　

Input

　　

Output

　　

Sample Input

　　5 3 25

Sample Output

　　1.9218750000

HINT

　　

Solution

　　考虑运用DP。

　　

Code

#include<iostream>  
#include<string>  
#include<algorithm>  
#include<cstdio>  
#include<cstring>  
#include<cstdlib>  
#include<cmath>
using namespace std;
typedef long long s64;
 
const int ONE = 800005;
const int MOD = 1e9 + 7;
const int all = 255;

int x, n;
double p;
double f[205][260][255][2];
double Ans;
int val, num;

int get() 
{ 
        int res;char c; 
        while( (c=getchar())<48 || c>57 );
        res=c-48;  
        while( (c=getchar())>=48 && c<=57 ) 
        res=res*10+c-48; 
        return res; 
} 

void Deal_first(int n)
{
        int record[250], num = 0, x = n;
        while(x)
            record[++num] = x & 1,
            x >>= 1;
        int j = 1, pos = 9, val = record[pos];
        for(pos = 9; pos + j - 1 <= num; j++)
            if(record[pos + j] != val) break;

        f[0][n & all][j][val] = 1; 
}

int Get(int x)
{
        int res = 0;
        while(x % 2 == 0) res++, x >>= 1;
        return res;
}

int main()
{
        x = get(), n = get(), p = (double)get() / 100;
        Deal_first(x);

        for(int i = 0; i < n; i++)
            for(int s = 0; s <= all; s++)
                for(int j = 1; j <= 250; j++)
                    for(int k = 0; k <= 1; k++)
                    {
                        val = s >> 8 - 1 & 1;
                        if(val != k) num = 1; else num = j + 1;
                        f[i + 1][s << 1 & all][num][val] += f[i][s][j][k] * p;

                        val = s == all ? (k ^ 1) : k;
                        if(val != k && k == 0) num = 1; else num = j;
                        f[i + 1][s + 1 & all][num][val] += f[i][s][j][k] * (1 - p);
                    }

        for(int s = 0; s <= all; s++)
            for(int j = 1; j <= 250; j++)
                for(int k = 0; k <= 1; k++)
                {
                    if(s == 0 && k == 0) val = j + 8;
                    else if(s == 0 && k == 1) val = 8;
                    else val = Get(s);
                    Ans += f[n][s][j][k] * val;
                }

        printf("%.8lf", Ans);
}

• Unkonwn