[ReVo_]

new bool:Alive[MAX_PLAYERS] = {true,...};

OnPlayerConnect:

Alive[playerid]=true;

OnPlayerDisconnect

Alive[playerid] = false;

OnPlayerDeath

Alive[playerid] = false;


Where u want to check

new alives = 0;
for ( new i = 0 , j = GetMaxPlayers( ) ; i < j ; ++ i ) {
if( ! IsPlayerConnected( i ) ) continue;
if( Alive[ i ] == false ) continue;
alives ++;
}

if ( alives == 1 ) {
SendClientMessageToAll( -1 , "one is alive" );
}