(a) turn = j is changed to turn = i for both processes

Process P0: Process P1;
repeat repeat
flag[0] := true; flag[1] := true;
// I wants in // I wants in
turn := 0; turn := 1;
// You have to wait for me // You have to wait for me
while (flag[1] & turn == 1); while(flag[0] & turn == 0);
CS CS
flag[0] := false; flag[1] := false;
// 0 is done // 1 is done
RS RS
forever forever

(b) the lines flag[i] = true and turn = j are reversed in both processes (it’s your turn, I want in)

Process P0: Process P1;
repeat repeat
turn := 1; turn := 0;
// it’s your turn // it’s your turn
flag[0] := true; flag[1] := true;
// but I want in // but I want in
while (flag[1] && turn == 1); while(flag[0] && turn == 0);
CS CS
flag[0] := false; flag[1] := false;
// 0 is done // 1 is done
RS RS
forever forever

( c ) flag[i] = true and turn = j are reversed in Pi (it’s your turn, I want in), but the other process, Pj, is left with the order flag[j] = true and turn = i (I want in, it’s your turn)

Process P0: Process P1;
repeat repeat
turn := 1; flag[1] := true;
// it’s your turn // I want in
flag[0] := true; turn := 0;
// I want in // it’s your turn
while (flag[1] && turn == 1); while(flag[0] && turn == 0);
CS CS
flag[0] := false; flag[1] := false;
// 0 is done // 1 is done
RS RS
forever forever