Submission #1606294

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

int main(){
    string s;
    cin>>s;
    set<char>f;
    set<char>::iterator ff;
    sort(s.begin(),s.end());
    for(long i=0;i<s.length();i++){
        f.insert(s[i]);
    }
    long len=f.size();
    char sa=s[len-1];
    vector<char>g;
    vector<char>::iterator gg;
    for(char i='a';i<=sa;i++){
        g.push_back(i);
    }
    long clock=0;
    gg=g.begin();
    ff=f.begin();
    while(gg!=g.end() && ff!=f.end()){
        if(*gg==*ff){
            clock++;
            gg++,ff++;
        }
        else if(*gg<*ff){
            gg++;
        }
        else ff++;
    }
    if(clock==g.size()) cout<<"None"<<endl;
    else{
        vector<long> z;
        vector<long>::iterator zz;
        vector<long>x;
        vector<long>::iterator xx;
        vector<long> y;
        vector<long>::iterator yy;
        for(ff=f.begin();ff!=f.end();ff++){
            z.push_back(*ff);
        }
      for(gg=g.begin();gg!=g.end();gg++){
          x.push_back(*gg);
      }
      for(xx=x.begin(),zz=z.begin();xx!=x.end(),zz!=z.end();xx++,zz++){
        if(*xx!=*zz){
            y.push_back(*xx);
        }
      }
      char sg;
      for(yy=y.begin();yy!=y.end();yy++){
        sg=*yy;
        cout<<sg;
        exit(0);
      }
    }
    return 0;
}

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