new PlayerShotPlayer[MAX_PLAYERS][MAX_PLAYERS];

public OnPlayerTakeDamage(playerid, issuerid, Float:amount, weaponid)
{
    PlayerShotPlayer[issuerid][playerid] = 1;
    return 0;
}

public OnPlayerDeath(playerid,killerid,reason)
{
    if(killerid != INVALID_PLAYER_ID)
    {
        if(!PlayerShotPlayer[killerid][playerid])
        {
            Ban(playerid);
        }
    }
    foreach(Player,i)
    {
        PlayerShotPlayer[i][playerid] = 0;
    }
    return 1;
}