trees_on_the_level_uva122b.cpp

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<vector>
#include<queue>
using namespace std;

const int maxn = 256 + 10;

struct Node{
  bool have_value;
  int v;
  Node* left, *right;
  Node():have_value(false),left(NULL),right(NULL){}
};

Node* root;

queue<Node*> freenodes; // 空闲列表
Node node[maxn]; // 内存池

void init() {
  for(int i = 0; i < maxn; i++)
    freenodes.push(&node[i]);
}

Node* newnode() {
  Node* u = freenodes.front();
  u->left = u->right = NULL; u->have_value = false; // 重新初始化该结点
  freenodes.pop();
  return u;
}

void deletenode(Node* u) {
  freenodes.push(u);
}

bool failed;
void addnode(int v, char* s) {
  int n = strlen(s);
  Node* u = root;
  for(int i = 0; i < n; 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;
}

void remove_tree(Node* u) {
  if(u == NULL) return;
  remove_tree(u->left);
  remove_tree(u->right);
  deletenode(u);
}

char s[maxn];
bool read_input() {
  failed = false;
  remove_tree(root);
  root = newnode();
  for(;;) {
    if(scanf("%s", s) != 1) return false;
    if(!strcmp(s, "()")) break;
    int v;
    sscanf(&s[1], "%d", &v);
    addnode(v, strchr(s, ',')+1);
  }
  return true;
}

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;
}

int main() {
  vector<int> ans;
  init();
  while(read_input()) {
    if(!bfs(ans)) failed = 1;
    if(failed) printf("not complete\n");
    else {
      for(int i = 0; i < ans.size(); i++) {
        if(i != 0) printf(" ");
        printf("%d", ans[i]);
      }
      printf("\n");
    }
  }
  return 0;
}