85pts求条 栈

#include<bits/stdc++.h>
using namespace std;
int main()
{
    long long s,n;
    cin>>n>>s;
    string str;
    cin>>str;
    deque<int>dq;
    while(s>0)
    {
        dq.push_back(s%2);
        s/=2;
    }
    for(int i=0;i<n;i++)
    {
        if(str[i]=='U'&&dq.size()>1)dq.pop_front();
        else dq.push_front(str[i]=='R');
    }
    long long x=0;
    while(dq.size())
    {
        x=x*2+dq.back();
        dq.pop_back();
    }
    cout<<x;
}