1 #include <bits/stdc++.h>
 2 #define LL long long
 3 #define lowbit(x) x&(-x)
 4 #define inf 0x3f3f3f3f
 5 #define eps 1e-5
 6 #define N 100005
 7 using namespace std;
 8 inline int ra()
 9 {
10     int x=0,f=1; char ch=getchar();
11     while (ch<‘0‘ || ch>‘9‘) {if (ch==‘-‘) f=-1; ch=getchar();}
12     while (ch>=‘0‘ && ch<=‘9‘) {x=x*10+ch-‘0‘; ch=getchar();}
13     return x*f;
14 }
15 int T;
16 int n,r,d[255];
17 double p[255];
18 double f[255][255],pw[255][255];
19 int main(int argc, char const *argv[])
20 {
21     T=ra();
22     while (T--)
23     {
24         n=ra(); r=ra();
25         memset(f,0,sizeof(f));
26         for (int i=1; i<=n; i++)
27         {
28             scanf("%lf",&p[i]);
29             d[i]=ra();
30         }
31         double ans=0;
32         for (int i=1; i<=n; i++)
33         {
34             pw[i][0]=1;
35             for (int j=1; j<=r; j++) pw[i][j]=pw[i][j-1]*(1-p[i]);
36         }
37         f[0][r]=1;
38         for (int i=0; i<n; i++)
39             for (int j=0; j<=r; j++)
40             {
41                 f[i+1][j]+=f[i][j]*pw[i+1][j];
42                 if (j-1>=0)
43                 {
44                     f[i+1][j-1]+=f[i][j]*(1-pw[i+1][j]);
45                     ans+=f[i][j]*(1-pw[i+1][j])*d[i+1];
46                 }
47             }
48         printf("%.10lf\n",ans);
49     }
50     return 0;
51 }

 1 #include <bits/stdc++.h>
 2 #define LL long long
 3 #define lowbit(x) x&(-x)
 4 #define inf 0x3f3f3f3f
 5 #define eps 1e-5
 6 #define N 100005
 7 using namespace std;
 8 inline int ra()
 9 {
10     int x=0,f=1; char ch=getchar();
11     while (ch<‘0‘ || ch>‘9‘) {if (ch==‘-‘) f=-1; ch=getchar();}
12     while (ch>=‘0‘ && ch<=‘9‘) {x=x*10+ch-‘0‘; ch=getchar();}
13     return x*f;
14 }
15 const int mod=1e9+7;
16 LL ans=1;
17 int n,m,x,y,cnt;
18 int head[100005],d[100005],b[100005];
19 LL f[100005],ine[200005];
20 vector<int> st;
21 struct edge{
22     int to,next;
23 }e[200005];
24 void insert(int x, int y)
25 {
26     e[++cnt].next=head[x]; e[cnt].to=y; head[x]=cnt;
27 }
28 void dp()
29 {
30     f[y]=ans;
31     for (int i=1; i<=n; i++) if (!d[i]) st.push_back(i);
32     while (!st.empty())
33     {
34         int now=st.back(); st.pop_back();
35         f[now]=f[now]*ine[b[now]]%mod;
36         for (int i=head[now];i;i=e[i].next)
37         {
38             f[e[i].to]=(f[e[i].to]+f[now])%mod;
39             d[e[i].to]--;
40             if (!d[e[i].to]) st.push_back(e[i].to);
41         }
42     }
43 }
44 int main(int argc, char const *argv[])
45 {
46     n=ra(); m=ra(); x=ra(); y=ra();
47     ine[1]=1;
48     for (int i=2; i<=m+1; i++) ine[i]=(-ine[mod%i]*(mod/i)+mod)%mod;//??
49     for (int i=1; i<=m; i++)
50     {
51         int xx=ra(),yy=ra();
52         insert(xx,yy);
53         d[yy]++;
54     }
55     d[y]++;
56     for (int i=1; i<=n; i++) b[i]=d[i];
57     for (int i=2; i<=n; i++)
58         ans=ans*d[i]%mod;
59     d[y]--;
60     if (y==1) {printf("%lld\n",ans); return 0;}
61     dp();
62     ans=(ans-f[x]+mod)%mod;
63     printf("%lld\n",ans);
64     return 0;
65 }

 1 #include <bits/stdc++.h>
 2 #define LL long long
 3 #define lowbit(x) x&(-x)
 4 #define inf 0x3f3f3f3f
 5 #define eps 1e-5
 6 #define N 100005
 7 using namespace std;
 8 inline int ra()
 9 {
10     int x=0,f=1; char ch=getchar();
11     while (ch<‘0‘ || ch>‘9‘) {if (ch==‘-‘) f=-1; ch=getchar();}
12     while (ch>=‘0‘ && ch<=‘9‘) {x=x*10+ch-‘0‘; ch=getchar();}
13     return x*f;
14 }
15 char a[205][205];
16 int f[205][205];
17 int xx[]={0,-1,1,0,0},yy[]={0,0,0,-1,1};
18 int q[205],pos[205],head,tail;
19 int n,m,sx,sy,K,ans;
20 void push(int now, int val)
21 {
22     if (val==-inf) return;
23     while (val-now>q[tail] && head<=tail) tail--;
24     q[++tail]=val-now;
25     pos[tail]=now;
26 }
27 void dp(int p, int x, int y, int d, int T)
28 {
29     head=1,tail=0; int now=1;
30     while (x<=n && y<=m && x>=1 && y>=1)
31     {
32         if (a[x][y]==‘x‘) head=1,tail=0;
33             else push(now,f[x][y]);
34         while (now-pos[head]>T && head<=tail) head++;
35         if (head<=tail) f[x][y]=q[head]+now;
36             else f[x][y]=-inf;
37         ans=max(ans,f[x][y]);
38         x+=xx[d]; y+=yy[d];
39         now++;
40     }
41 }
42 int main(int argc, char const *argv[])
43 {
44     n=ra(); m=ra(); sx=ra(); sy=ra(); K=ra();
45     for (int i=1; i<=n; i++) scanf("%s",a[i]+1);
46     for (int i=1; i<=n; i++)
47         for (int j=1; j<=m; j++)
48             f[i][j]=-inf;
49     f[sx][sy]=0;
50     for (int i=1; i<=K; i++)
51     {
52         int x=ra(),y=ra(),d=ra();
53         if (d==1) for (int j=1; j<=m; j++) dp(i,n,j,d,y-x+1);
54         if (d==2) for (int j=1; j<=m; j++) dp(i,1,j,d,y-x+1);
55         if (d==3) for (int j=1; j<=n; j++) dp(i,j,m,d,y-x+1);
56         if (d==4) for (int j=1; j<=n; j++) dp(i,j,1,d,y-x+1);
57     }
58     printf("%d\n",ans);
59     return 0;
60 }