Codeforces Round #272 (Div. 2), problem: (B) Dreamoon and WiFi

#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define pii pair<int,int>
#define pli pair<long long int,int>
#define pbi pair<bool,int>
#define pob pop_back
#define all(a) a.begin(),a.end()
#define fio ios_base::sync_with_stdio(false); cin.tie(NULL);cout.tie(NULL);
#define i64 long long int
#define mem(x,y) memset(x,y,sizeof(x))
#define fill(arr,b) fill(arr, arr+sizeof(arr)/sizeof(arr[0]), b)
#define maxarr(n,arr,m) m=-1e9;for(int i=0;i<n;i++)if(arr[i]>m) m=arr[i];
#define read freopen("input.txt","r",stdin);
#define sortd(x,y) sort(x,y,greater<int>());
#define F first
#define S second

const int maxn = (i64)1e9+7;
const double pi = acos(-1.0);

//bool fne(const pii &a, const pii &b){return (a.F > b.F)||(a.F==b.F&&a.S>b.S);}
//bool sne(const pii &a, const pii &b){return (a.S < b.S)||(a.S==b.S&&a.F<b.F);}
//bool isprime(int n){for(int i=2;i*i<=n;i++){if(n%i==0)return false;}return true;}

int cnt=0,cur1=0;
void dp(int x,int cur2){
    if(x==0){
        if(cur2==cur1) cnt++;
        return;
    }
    dp(x-1,cur2-1);
    dp(x-1,cur2+1);
}
int main(){
    fio;
    string s1,s2;
    cin>>s1>>s2;
    int n=s1.size();
    int cur2=0,x=0;
    for(int i=0;i<n;i++){
        s1[i]=='+'?cur1++:cur1--;
        s2[i]=='+'?cur2++:s2[i]=='-'?cur2--:x++;
    }
    dp(x,cur2);
    x=1<<x;
    double ans= cnt/(1.0*x);
    cout<<fixed<<setprecision(12)<<ans;
    return 0;
}