exclusively for t.me/cxx95

gen_three_diffs.cpp

#include "testlib.h"
#include <bits/stdc++.h>
using namespace std;
 
void diffize(vector<int>& vec1, vector<int>& vec2, int s) {
    int m = vec1.size();
 
    int diffs = 0;
    for (int i = 0; i < m; ++i) {
        if (vec1[i] != vec2[i]) {
            ++diffs;
        }
    }
 
    while (diffs < 3) {
        ++diffs;
        int ind = -1;
        while (ind < 0 || vec1[ind] != vec2[ind]) {
            ind = rnd.next(m);
        }
        while (vec1[ind] == vec2[ind]) {
            vec2[ind] = rnd.next(1, s);
        }
    }
}
 
int main(int argc, char **argv) {
    registerGen(argc, argv, 1);
 
    int n = atoi(argv[1]);
    int m = atoi(argv[2]);
    int s = atoi(argv[3]);
 
    // initial answer
    vector<int> answer(m);
    for (int i = 0; i < m; ++i) {
        answer[i] = rnd.next(1, s);
    }
 
    // the answer is NO
    vector<vector<int>> ans;
    for (int i = 0; i < n; ++i) {
        int ind = rnd.next(m);
 
        int prev = answer[ind];
        while (answer[ind] == prev) {
            answer[ind] = rnd.next(1, s);
        }
        ans.push_back(answer);
 
        answer[ind] = prev;
    }
 
    int ind1 = rnd.next(n);
    int ind2 = ind1;
    while (ind1 == ind2) {
        ind2 = rnd.next(n);
    }
 
    diffize(ans[ind1], ans[ind2], s);
 
    cout << n << " " << m << endl;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            cout << ans[i][j];
            if (j != m - 1) {
                cout << " ";
            }
        }
        cout << endl;
    }
}