UVa 122 Trees on the level（链式二叉树的建立和层次遍历）

题目链接：

https://cn.vjudge.net/problem/UVA-122

 /*
 问题
 给出每个节点的权值和路线，输出该二叉树的层次遍历序列。

 解题思路
 根据输入构建链式二叉树，再用广度优先遍历保存权值最后输出。
 */
 #include<cstdio>
 #include<cstring>
 #include<vector>
 #include<queue>
 using namespace std;
 const int maxn=;
 bool failed;

 struct NODE{
     bool have_value;
     int v;
     NODE *left,*right;
     NODE() : have_value(false),left(NULL),right(NULL){};
 };
 NODE* newnode(){
     return new NODE();
 }
 NODE* root;

 bool read_input();
 void addnode(int v,char *s);
 bool bfs(vector<int> &ans);
 void remove_tree(NODE* u){
     if(u == NULL) return;
     remove_tree(u->left);
     remove_tree(u->right);
     delete u;
 }

 int main()
 {
     //freopen("E:\\testin.txt","r",stdin);
     vector<int> ans;
     while(read_input()){
         if(failed || !bfs(ans))
             printf("not complete\n");
         else{
             int i;
             for(i=;i<ans.size()-;i++)
                 printf("%d ",ans[i]);
             printf("%d\n",ans[i]);
         }
     }
     return ;
 }

 bool bfs(vector<int> &ans){
     queue<NODE*> q;
     ans.clear();
     q.push(root);

     while(!q.empty()){
         NODE* u =q.front(); q.pop();
         if(!u->have_value)    return false;
         ans.push_back(u->v);

         if(u->left != NULL)    q.push(u->left);
         if(u->right != NULL) q.push(u->right);
     }
     return true;
 }
 void addnode(int v,char *s){
     int len=strlen(s);

     NODE* u= root;
     for(int i=;i<len;i++){
         if(s[i] == 'L'){
             if(u->left == NULL)
                 u->left= newnode();
             u=u->left;
         }else if(s[i] == 'R'){
             if(u->right == NULL)
                 u->right= newnode();
             u=u->right;
         }
     }

     if(u->have_value)    failed=true;
     u->v= v;
     u->have_value=true;
 }
 bool read_input(){
     char s[maxn];
     failed=false;
     remove_tree(root);
     root=newnode();
     for(;;){
         if(scanf("%s",s) != )    return false;
         if(!strcmp(s,"()"))    break;
         int v;
         sscanf(s+,"%d",&v);
         addnode(v,strchr(s,',')+);
     }
     return true;
 }