CodeForces 412C 手速题

//CodeForces 412C

#include "iostream"
#include "cstdio"
#include "cstring"
#include "algorithm"
#include "vector"
using namespace std;
vector<string> str;
int n;
string res;

int  main()
{
    int i, j;
    scanf("%d", &n);
    str.resize(n + 1);
    for(i = 1; i <= n; ++i) {
        cin >> str[i];
    }
    int len = str[1].size();
    for(i = 0; i <= len - 1; ++i) {
        char c = str[1][i];
        bool match = 1;
        for(j = 2; j <= n; ++j) {
            if(c == '?') {
                c = str[j][i];
            }
            else {
                if(c == str[j][i] || str[j][i] == '?') {
                    continue;
                }
                else {
                    match = 0;
                    break;
                }
            }
        }
        if(!match)
            res.push_back('?');
        else
            res.push_back(c == '?'? 'x': c);
    }
    cout<<res<<endl;
}