03-树2 List Leaves (25分)

#include<stdio.h>
#include<ctype.h>

struct Node{
int root;
int left;
int right;
};

int main(){
//create the tree
int n;
struct Node nodes[10];
scanf("%d",&n);
for(int i=0;i<n;i++){
nodes[i].root = 1;
nodes[i].left = -1;
nodes[i].right = -1;
}
for(int i=0;i<n;i++){
char ch1,ch2;
scanf("\n%c %c",&ch1,&ch2);
if(isdigit(ch1)){
nodes[i].left = ch1 - '0';
nodes[ch1-'0'].root = 0;
}
if(isdigit(ch2)){
nodes[i].right = ch2 - '0';
nodes[ch2-'0'].root = 0;
}
}
int root;
for(int i=0;i<n;i++)
{
if(nodes[i].root == 1){
root = i;
break;
}
}
//find the leave and print it;
int leaves = 0;
int queue[10];
int head=0,rear=0;

queue[rear++] = root;
while(rear-head){
int node = queue[head++];
if(nodes[node].left == -1 && nodes[node].right == -1){
if(leaves)
printf(" ");
printf("%d",node);
++leaves;
}
if(nodes[node].left != -1){
queue[rear++] = nodes[node].left;
}
if(nodes[node].right != -1){
queue[rear++] = nodes[node].right;
}
}

return 0;
}