B_Dreamoon_and_WiFi.cpp

#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h> 
#include <complex>
#include <queue>
#include <set>
#include <unordered_set>
#include <list>
#include <chrono>
#include <random>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <map>
#include <unordered_map>
#include <stack>
#include <iomanip>
#include <fstream>
 
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef pair<int,int> p32;
typedef pair<ll,ll> p64;
typedef pair<double,double> pdd;
typedef vector<ll> v64;
typedef vector<int> v32;
typedef vector<vector<int> > vv32;
typedef vector<vector<ll> > vv64;
typedef vector<vector<p64> > vvp64;
typedef vector<p64> vp64;
typedef vector<p32> vp32;
ll MOD = 998244353;
double eps = 1e-12;
#define forn(i,e) for(ll i = 0; i < e; i++)
#define forsn(i,s,e) for(ll i = s; i < e; i++)
#define rforn(i,s) for(ll i = s; i >= 0; i--)
#define rforsn(i,s,e) for(ll i = s; i >= e; i--)
#define ln "\n"
#define dbg(x) cout<<#x<<" = "<<x<<ln
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define INF 2e18
#define fast_cin() ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())


int main()
{
 fast_cin();
 string a1,a2;
 cin>>a1>>a2;
 int count1=0,count_quesmark=0,count2=0;
 double total_ways=0;
 for(int i=0;i<a1.length();i++)
 {
     if(a1[i]=='+')
     count1++;
     else
     count1--;
 }
 for(int i=0;i<a2.length();i++)
 {
     if(a2[i]=='?')
     count_quesmark++;
     else if(a2[i]=='+')
     count2++;
     else
     count2--;
 }
 int diff=count1-count2;
 double ans;
 if(count_quesmark<abs(diff) || (count_quesmark+abs(diff))%2==1)
 cout<<0;
 else
 {
     int c=1;
     int m=(count_quesmark+abs(diff))/2;
     for(int i=0;i<m;i++)
     {
         c*=(count_quesmark-i);
     }
     for(int i=2;i<=m;i++)
     {
         c/=i;
     }
     ans=(double)c/(1<<count_quesmark);
     cout<<setprecision(12)<<ans;
 }
 return 0;
}