UVa 122 树的层次遍历

题意：

给定一颗树， 按层次遍历输出。

分析：

用数组模拟二叉树， bfs即可实现层次遍历

 #include <bits/stdc++.h>
 using namespace std;
 struct Node{
     bool have_value;
     int v, left, right;
     void reset(){//用于再次初始化节点
         init();
     }
     void init(){
         have_value = ;
         v = left = right = ;
     }
     Node():have_value(false), v(),left(), right(){init();}//构造函数
 };
 const int maxn = ;
 Node tree[maxn];
 const int root = ;
 int cnt, failed;
 char s[maxn];
 void newtree(){
     cnt = ;
     tree[root].reset();
 }
 void addnode(int v, char* s){

     int len = strlen(s) - ;
     int u = root;
     for(int i = ; i < len; i++){
         if(s[i] == 'L'){
             if(tree[u].left == )
             {
                 tree[u].left = ++cnt;
                 tree[cnt].reset();
                 u = cnt;
             }
             else { u = tree[u].left;};
         }
         else if(s[i] == 'R'){
             if(tree[u].right == ){
                 tree[u].right = ++cnt;
                 tree[cnt].reset();
                 u = cnt;
             }
             else u = tree[u].right;
         }
     }
     if(tree[u].have_value) failed = true;
     tree[u].v = v;
     tree[u].have_value = true;
 }
 bool input(){
     newtree();
     failed = false;
     for(;;){
         if(scanf("%s",s) != ) return false;
         if(!strcmp(s,"()")) break;
         int v;
         sscanf(&s[],"%d",&v);
         addnode(v,strchr(s,',')+);//将逗号后的字符串传递
     }
     return true;
 }
 bool bfs(vector<int>& ans){//引用传递
     queue<int> q;
     q.push(root);
     while(!q.empty()){
         int u = q.front();
         q.pop();
         if(tree[u].have_value == )
             return false;
         ans.push_back(tree[u].v);
         if(tree[u].left != ){
             q.push(tree[u].left);
         }
         if(tree[u].right != ){
             q.push(tree[u].right);
         }
     }
     return true;
 }
 int main(){

     while(input()){
         vector<int> ans;
         if(!bfs(ans) || failed)
             printf("not complete\n");
         else {
             cout <<ans[];
             int alen = ans.size();
             for(int i = ; i < alen; i++){
                 cout << " " << ans[i];
             }
             puts("");
         }
     }
     return ;
 }