解题报告-PAT-List Leaves

# include 
# include 
# include 
# include 
# include 
# define MAX 10
# define Null -1
typedef struct node{
	int left;
	int right;
}Tree;

int main(){
	
	Tree tree[MAX];
	int q[MAX];
	char l,r;
	int n,root;
	int flag[MAX]={0};
	scanf("%d\n",&n);
	for(int i = 0; i < n; i++){
		scanf("%c %c",&l,&r);
		getchar();
		if(l == '-') tree[i].left = Null;
		else{
			tree[i].left = l-'0';
			flag[l-'0'] = 1; // 表示这个节点已经出现过 
		}
		if(r == '-') tree[i].right = Null;
		else{
			tree[i].right = r-'0';
			flag[r-'0'] = 1;
		} 
	}
	for(int i = 0; i < n; i++){
		if(!flag[i]){
			root = i;
			break;
		}	
	}
	
	q[0]=root; 
	int p;
	int front = 0, rear = 1;
	int temp = 0;
	//层次遍历寻找叶子节点
	while(front < rear){
		
		
		p=q[front++];
		if(tree[p].left!=Null)
			q[rear++] = tree[p].left;
		if(tree[p].right!=Null)
			q[rear++] = tree[p].right;
		if(tree[p].left==Null && tree[p].right==Null)
		{
			if(temp) printf(" ");
				temp++;
			printf("%d",p);
		}
	}
	 
	
	return 0;
}