Codeforces Round #92 (Div. 2 Only), problem B

#include <algorithm>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <numeric>
#include <iterator>
#include <stack>
#include <list>


#define fori(i,start,end) for(int(i)=int(start);(i)<int(end);(i)++)
#define all(a) (a).begin(), (a).end()
#define rep(i, end) fori((i), 0, (end))

using namespace std;

#ifndef ONLINE_JUDGE
void compare(int test_number, stringstream& output, stringstream& solution) {
        cout << "Test " << test_number << ": ";
        if (solution.str() != output.str()) {
            cout << "not ok. Expected:\n" << solution.str() << "\nRecieved:\n" << output.str() << "\n";
        } else {
            cout << "ok.\n";
        }
}
#endif



string rearrange(string& s, vector<int>& perm) {
    string ret;
    rep(i, perm.size()) {
        ret.push_back(s[perm[i]]);
    }
    return ret;
}

int rearrange_convert(vector<int>& v, vector<int>& perm) {
    int ret = 0;
    rep(i, perm.size()) {
        ret = ret*10 + v[perm[i]];
    }
    return ret;
}

template<class T> T convert(const string& s) {T ret; istringstream iss(s); iss >> ret; return ret; }

void f(istream& input, ostream& output) {
    int n, k;
    input >> n >> k;
    vector<vector<int> > num(n, vector<int>(k));
    rep(i,n) {
        string s;
        input >> s;
        rep(j, k) num[i][j] = s[j] - '0';
    }

    vector<int> perm;
    rep(i,k) perm.push_back(i);

    int min = 100000000;
    vector<int> d(n);
    do {
        rep(i, n) {
            d[i] = rearrange_convert(num[i], perm);
        }
        sort(all(d));
        min = std::min(min, d[n-1] - d[0]);
    } while (next_permutation(all(perm)));

    output << min;
}


void f1(istream& input, ostream& output) {
    vector<string> num;
    int n, k;
    input >> n >> k;
    rep(i,n) {
        string s;
        input >> s;
        num.push_back(s);
    }

    vector<int> perm;
    rep(i,k) perm.push_back(i);

    int min = 100000000;
    do {
        vector<int> d;
        rep(i, n) {
            const string& tmp = rearrange(num[i], perm);
            d.push_back(convert<int>(tmp));
        }
        sort(all(d));
        min = std::min(min, d[n-1] - d[0]);
    } while (next_permutation(all(perm)));

    output << min;
}

int main() {
#ifdef ONLINE_JUDGE
    f(cin, cout);
#else
    {
        stringstream input;
        input << "6 4\n5237\n2753\n7523\n5723\n5327\n2537";
        stringstream solution;
        solution << "2700";

        stringstream output;
        f(input, output);

        compare(0, output, solution);
    }
    {
        stringstream input;
        input << "3 3\n010\n909\n012";
        stringstream solution;
        solution << "3";

        stringstream output;
        f(input, output);

        compare(1, output, solution);
    }
    {
        stringstream input;
        input << "7 5\n50808\n36603\n37198\n44911\n29994\n42543\n50156";
        stringstream solution;
        solution << "20522";

        stringstream output;
        f(input, output);

        compare(2, output, solution);
    }
    {
        stringstream input;
        input << "8 8\n96805230\n73119021\n06552907\n86283347\n88650846\n19155689\n37032451\n19310120";
        stringstream solution;
        solution << "53604668";

        stringstream output;
        f(input, output);

        compare(3, output, solution);
    }



#endif
    return 0;
}