【紫书】Trees on the level UVA

题意：给你一些字符串，代表某个值被插入树中的位置。让你输出层序遍历。

题解：动态建树。

　　　由于输入复杂，将输入封装成read_input。注意输入函数返回的情况

　　　再将申请新节点封装成newnode().

　　　最后层序输出直接用bfs实现。

坑：我把ans.clear放到主程序的if里面，导致某特定情况无法初始化，wa了一页//以后debug真的别XJB改细节了上下语句顺序，一些无关紧要的处理，改之前想一想

#define _CRT_SECURE_NO_WARNINGS
#include "stdio.h"
#include<stdio.h>
#include<algorithm>
#include<string>
#include<vector>
#include<list>
#include<set>
#include<iostream>
#include<string.h>
#include<queue>
using namespace std;
const int maxn = 300;
char s[maxn];
int failed;
struct node {
    int v;
    bool have_v;
    node* leftson, *rightson;
    node() :have_v(false), leftson(NULL), rightson(NULL) {}
}*root;
node* newnode() { return new node(); }
void addnode(int v, char *s) {
    int n = strlen(s);
    node * now = root;

    for (int i = 0; i < n - 1; i++) {
        if (s[i] == 'L') {

            if (now->leftson == NULL) now->leftson = newnode();
            now = now->leftson;
        }
        else {
            if (now->rightson == NULL) now->rightson = newnode();
            now = now->rightson;
        }

    }
    if (now->have_v) { failed = 1; }
    now->v = v;
    now->have_v = 1;
}
bool read_input() {
    failed = false; root = newnode();
    while (1) {
        while (scanf("%s", &s) != 1)return false;
        if (s[1] == ')')break;
        int v;
        sscanf(&s[1], "%d", &v);
        addnode(v, strchr(s, ',') + 1);
    }
    return true;
}
list<int>ans;
void bfs() {
    ans.clear();
    queue<node> Q;
    node now;
    //int vis[maxn];
    Q.push(*root);
    while (!Q.empty()) {
        now = Q.front(); if (!now.have_v) { failed = 1; break; }
        Q.pop();
        if (now.leftson != NULL)Q.push(*now.leftson);
        if (now.rightson != NULL)Q.push(*now.rightson);
        ans.push_back(now.v);
    }

}
int main() {
    while (read_input()) {
        bfs();
        if (failed)cout << "not complete" ;
        else
        {
            cout << ans.front(); ans.pop_front();
            for (auto t : ans)cout << ' ' << t;
        }
        cout << endl;
    }

    system("pause");
}