问答题 【程序说明】 本程序先从文件读人各考生的准考证号(设为整型数)及成绩，并将其存放在一棵检索二叉树上，二叉树结点的健值是成绩，每个结点带一链表，链表结点存放取得该成绩的考生的准考证号。然后，程序按中序遍历检索二叉树，从高分到低分输出结果，使每行输出成绩及其取得成绩的考生的准考证号。 【程序】 #include ＜ stdio. h ＞ typedef struet idnode { int id; struct idnode * next; } ldNode; typedef struct marknode I int mark; ldNode * head; struct marknode * left, * right; } MarkNode; char fname [ ] = "sp07.dat"; main( ) { int id, mark; MarkNode * root = null; FILE * fp = fopen(fname," r" ); if(!fp) { printf("file%s open error, /n" , fname); exit(0); } while (!feop(fp)) { fscanf(fp," %d%d", &id, &mark); btree(&root, id, mark); } fclose(fp); print(root); } btree(MarkNod * * mpptr, int id, int mark) { ldNode * ip; MarkNode *mp = * mpptr; if{{U}} (1) {{/U}}{ if (mark==p-＞mark) addldNODE ({{U}} (2) {{/U}}, id); else if ( mark ＞mp -＞ mark) btree (&top -＞ left, id, mark); else btree(&mp-＞ right, id, mark); } else Imp = ( marknode * ) malloc(sizeo (marknode) ); mp -＞ mark = mark; mp -＞ left =mp -＞ right = NULL; {{U}}(3) {{/U}} addldNode(&mp -＞ head, id); {{U}}(4) {{/U}}; } } addldNode(ldNode * * ipp, int id) { ldNode * ip = * ipp; if ({{U}} (5) {{/U}})addldNode ({{U}} (6) {{/U}}), id; else { ip = (ldNode * )malloc(sizeof(ldNode) ); sp - ＞ id = id; ip -＞ next = NULL; {{U}} (7) {{/U}} } } print(MarkNode * rap) { ldNode *ip, *ip0; if (mp) { print ( mp -＞ left); printf(" %6d: /t" ,mp -＞ mark); ip = mp -＞ head; while(ip) { printf(" %6d" ,ip -＞ id); ip0 =ip; ip = ip -＞ next; free (ip0); } printf(" /n" ); printf( mp -＞ right); free(mp); } }