PTA——输出树的叶结点

 1 #include <stdio.h>
 2 #include <queue>
 3 #define MaxTree 20
 4 #define Null -1
 5 using namespace std;
 6 
 7 struct TreeNode {
 8     int Left;
 9     int Right;
10 } T[MaxTree];
11 int N,check[MaxTree];
12 int count = 0;
13 
14 int BuildTree(struct TreeNode T[]) {
15     int Root = Null,i;
16     char cl,cr;
17     scanf("%d\n",&N);
18     if(N) {
19         for(i=0; i<N; i++) check[i]=0;
20         for(i=0; i<N; i++) {
21             scanf("%c %c\n",&cl,&cr);
22             if(cl==‘-‘ && cr==‘-‘) count++;
23             if(cl!=‘-‘) {
24                 T[i].Left = cl-‘0‘;
25                 check[T[i].Left]=1;
26             } else T[i].Left=Null;
27             if(cr!=‘-‘) {
28                 T[i].Right = cr-‘0‘;
29                 check[T[i].Right]=1;
30             } else T[i].Right=Null;
31         }
32         for(i=0; i<N; i++)
33             if(!check[i]) break;
34         Root = i;
35     }
36     return Root;
37 }
38 
39 int main() {
40     queue<int> Q;
41     int R,tmp;
42     R=BuildTree(T);
43     if(R==Null) return 0;
44     Q.push(R);
45     while(!Q.empty()) {
46         tmp = Q.front();
47         Q.pop();
48         if(T[tmp].Left==-1 && T[tmp].Right==-1){
49             printf("%d",tmp);
50             count--;
51             if(count!=0) printf(" ");
52         }
53         if(T[tmp].Left!=-1) Q.push(T[tmp].Left);
54         if(T[tmp].Right!=-1) Q.push(T[tmp].Right);
55     }
56     return 0;
57 }