Ratsun reitit

#include <iostream>
#include <map>
#include <vector>
#include <array>
 
using namespace std;
 
const array<pair<int, int>, 8> moves = {pair<int,int>(2,1), pair<int,int>(1,2), pair<int,int>(-2,1), pair<int,int>(-1,2), pair<int,int>(2,-1), pair<int,int>(1,-2), pair<int,int>(-2,-1), pair<int,int>(-1,-2)};
 
int main(){
    map<int, vector<pair<int, int>>> a;
    map<pair<int, int>, int> b;
 
    int n, cmove = 0;
    cin >> n;
    int remaining = n*n - 1; //remove start grid
 
    // Initialize 0,0
    a[0].push_back(pair<int, int>(0,0));
    b[pair<int, int>(0,0)] = 0;
    
 
    while (true){
        for (auto & it : a[cmove]){
            vector<pair<int, int>>& c = a[cmove + 1];
            vector<pair<int,int>> r;
            for(auto const& it2 : moves){
                int first = it2.first + it.first;
                int second = it2.second + it.second;
                if(first >= 0 && first < n && second >= 0 && second < n){
                    pair<int,int> p(first, second);
                    if(b.count(p) == 0) {
                        r.push_back(p);
                        b[p] = cmove + 1;
                        remaining--;
                    }
                }
            }
            c.insert(c.end(), r.begin(), r.end());
            
        }
        if(remaining <= 0){
            break;
        }
        cmove++;
    }
 
    for(int x = 0; x < n; x++){
        for(int y = 0; y < n; y++){
            cout << b[pair<int, int>(x,y)] << " ";
        }
        cout << "\n";
    }
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: ACCEPTED

Test 5

Group: 1, 2, 3

Verdict: ACCEPTED

Test 6

Group: 1, 2, 3

Verdict: ACCEPTED

Test 7

Group: 1, 2, 3

Verdict: ACCEPTED

Test 8

Group: 2, 3

Verdict: ACCEPTED

Test 9

Group: 2, 3

Verdict: ACCEPTED

Test 10

Group: 2, 3

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED