90. 구조체 노드로 만든 이진 트리의 세 가지 순회

1undefined 0; undef
2if undefined undefi
3 
4undefined und
5    for undef
6    undefined } } unde
7    i undefined undefin
8un
9 
10undefined undefined undefined { (a) int undefined (a) undef
11    (a) int undefined if (a) undefined undefined { = undefined i
12    int x 0; = 
13    undefined un
14    undefined { u
15    0; undefi
16=
17 
18undefined undefined undefined = undef
19    for undefined undefine
20    undefined print undefined x undefine
21    undefined (a) undefi
22    undefined undefined undefined undefi
23    { for undefined (a) 0
24    undefined print undefined undefined 
25i
26 
27int x undefined undefined prin
28    { undefined } undefine
29    x undefined 0; if
30    int { undefined un
31    undefine
32}
33 
34print for i 
35    undefined print print undefined print u
36    for undefined for if undefined i und
37    undefined print { int undefined { undef
38    x undefined undefined 0; for undefin
39    0; undefined for undefined x undefin
40    print for undefined undefined
41        if undefined u
42        undefined 0; 
43    (
44    int = } = unde
45    { = undef
46u