Cod sursă (job #238915)

#include <fstream>

using namespace std;

ifstream fin ("hex.in");
ofstream fout ("hex.out");

struct perechi
{
    int x, y, mx;
    bool clr;
}lee[250001];
int a[501][501], x, y, n, ind, mx = 1000000000;

void ok (int i, int j, int clr, int px)
{
    if (i > n || j > n || i < 1 || j < 1)return;
    if(a[i][j] == -1)return;
    if (a[i][j]%2 != clr)return;

    lee[++ind].x=i;
    lee[ind].y=j;
    lee[ind].clr = clr;
    lee[ind].mx = max(px, a[i][j]);

    a[i][j]=-1;
    return;
}
int main()
{
    fin >> n;
    for (int i =1; i<= n*n; i++)
    {
        fin >> x >> y;
        a[x][y]=i;
    }
    for (int i = 1; i <=n; i++)
    {
        if(a[1][i]%2 == 0)//e albastru
        {
            lee[++ind].x=1;
            lee[ind].y=i;
            lee[ind].clr = 0;// 0 = albastru
            lee[ind].mx = i;

            a[1][i] = -1;
        }
        if(a[i][1]%2 == 1)//e rosu
        {
            lee[++ind].x=i;
            lee[ind].y=1;
            lee[ind].clr = 1; //1 = rosu
            lee[ind].mx = i;

            a[i][1] = -1;
        }
    }
    for (int i =1; i<=ind; i++)
    {
        x = lee[i].x;
        y = lee[i].y;

        if (lee[i].clr == 0 && lee[i].x == n)mx = min(mx, lee[i].mx);
        else if (lee[i].clr == 1 && lee[i].y == n)mx = min(mx, lee[i].mx);
        else
        {
            ok(x + 1, y, lee[i].clr, lee[i].mx);
            ok(x, y + 1, lee[i].clr, lee[i].mx);
            ok(x + 1, y - 1, lee[i].clr, lee[i].mx);

            if (lee[i].clr == 0)ok(x, y - 1, lee[i].clr, lee[i].mx);
            else ok(x - 1, y + 1, lee[i].clr, lee[i].mx);
        }
    }

    fout << mx;
    return 0;
}