1110. Complete Binary Tree (25)

1110. Complete Binary Tree (25)
时间限制 400 ms 内存限制 65536 kB 代码长度限制 16000 B
判题程序 Standard 作者 CHEN, Yue

Given a tree, you are supposed to tell if it is a complete binary tree.
Input Specification:
Each input file contains one test case. For each case, the first line gives a positive integer N (<=20) which is the total number of nodes in the tree – and hence the nodes are numbered from 0 to N-1. Then N lines follow, each corresponds to a node, and gives the indices of the left and right children of the node. If the child does not exist, a “-” will be put at the position. Any pair of children are separated by a space.
Output Specification:
For each case, print in one line “YES” and the index of the last node if the tree is a complete binary tree, or “NO” and the index of the root if not. There must be exactly one space separating the word and the number.
Sample Input 1:
9
7 8
- -
- -
- -
0 1
2 3
4 5
- -
- -
Sample Output 1:
YES 8
Sample Input 2:
8
- -
4 5
0 6
- -
2 3
- 7
- -
- -
Sample Output 2:
NO 1

借助stringstram来输入是非常方便的啦

#define _CRT_SECURE_NO_WARNINGS
#include <algorithm>
#include <iostream>
#include <string>
#include <sstream>
#include <queue>
#include <cstring>

using namespace std;
const int MaxN = 30;

typedef struct tnode {
    int lchild;
    int rchild;
}TNode;

TNode Tree[MaxN];int N;
bool isRoot[MaxN];

int CreateTree() {
    memset(Tree, -1, sizeof(TNode) * (N + 1));
    memset(isRoot, 1, N + 1);
    string line; stringstream ss; int cid;
    for (int i = 0; i < N; ++i) {
        getline(cin, line); 
        ss.clear(); ss.str("");
        ss << line;
        if (line[0] == '-') {
            ss.get();
            if (line[2] != '-') {
                ss >> cid;
                Tree[i].rchild = cid;
                isRoot[cid] = false;
            }
        }
        else {
            ss >> cid;
            Tree[i].lchild = cid;
            isRoot[cid] = false;

            int idx = 0;
            while (line[idx++] != ' ');
            if (line[idx] != '-') {
                ss >> cid;
                Tree[i].rchild = cid;
                isRoot[cid] = false;
            }
        }
    }

    int root = 0;
    while (!isRoot[root])++root;
    return root;

}

bool isCBT(int root,int & last) {
    queue<int>que; que.push(root);
    while (que.size()) {
        int node = que.front(); que.pop();
        if (node == -1)break;
        else last = node;
        que.push(Tree[node].lchild);
        que.push(Tree[node].rchild);
    }

    while (que.size()) {
        int node = que.front(); que.pop();
        if (node != -1)return false;
    }

    return true;
}


int main() {
#ifdef _DEBUG
    freopen("data.txt", "r+", stdin);
#endif // _DEBUG

    std::ios::sync_with_stdio(false);

    cin >> N; cin.get();
    int root = CreateTree(),last;
    bool CBTTree = isCBT(root, last);
    CBTTree ? (cout << "YES " << last) : (cout << "NO " << root);
    return 0;
}