A1110. Complete Binary Tree (25)

题目描述

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

参考代码

#include <cstdio>
#include <queue>
#include <malloc.h>
#include <vector>
#include <string.h>

using namespace std;

const int maxn = 30;

int n;

bool vis[maxn] = {false};

struct tt
{
	char l[3];
	char r[3];
	int l_int;
	int r_int;
}number[maxn];

struct Node
{
	int data;			
	Node * lchild;
	Node * rchild;
};

Node * result;

Node * createTree(int k)
{
	queue<Node *> q;
	Node * root = (Node *)malloc(sizeof(Node));
	root->data = k;
	root->lchild = NULL;
	root->rchild = NULL;
	q.push(root);
	while(!q.empty())
	{
		Node * node = q.front();
		int node_index = node->data;
		q.pop();
		if(strcmp(number[node_index].l,"-") != 0)
		{
			Node * lch = (Node *)malloc(sizeof(Node));
			lch->data = number[node_index].l_int;
			lch->lchild = NULL;
			lch->rchild = NULL;
			node->lchild = lch;
			q.push(lch);
		}
		if(strcmp(number[node_index].r,"-") != 0)
		{
			Node * rch = (Node *)malloc(sizeof(Node));
			rch->data = number[node_index].r_int;
			rch->lchild = NULL;
			rch->rchild = NULL;
			node->rchild = rch;
			q.push(rch);
		}
	}
	return root;
}
vector<Node *> v; 
bool isCompleteBinaryTree(Node * root)
{
	queue<Node *> q;
	v.push_back(root);
	q.push(root);
	while(!q.empty())
	{
		Node * node = q.front();
		q.pop();
		v.push_back(node->lchild);
		v.push_back(node->rchild);
		if(node->lchild != NULL)
		q.push(node->lchild);
		if(node->rchild != NULL)
		q.push(node->rchild);
	}
	int count = 0;
	for(int i=0;i<v.size();i++)
	{
		if(v[i] != NULL)
		{
			count++;
			result = v[i];
		}
		else
		{
			if(count == n)
			{
			return true;
			}
			else
			{
				return false;
			}
		}
	}
}

int main()
{
	int k;
	Node * root;
	scanf("%d",&n);
	getchar();
	for(int i=0;i<n;i++)
	{
		scanf("%s %s",number[i].l,number[i].r);
		getchar();
	}
	for(int i=0;i<n;i++)
	{
		if(strcmp(number[i].l,"-") != 0)
		{
			int result = 0;
			for(int j=0;j<strlen(number[i].l);j++)
			{
				result = result * 10 + number[i].l[j] - '0';
			}
			number[i].l_int = result;
			vis[number[i].l_int] = true;
		}
		if(strcmp(number[i].r,"-") != 0)
		{
			int result = 0;
			for(int j=0;j<strlen(number[i].r);j++)
			{
				result = result * 10 + number[i].r[j] - '0';
			}
			number[i].r_int = result;
			vis[number[i].r_int] = true;
		}
	}
	for(int i=0;i<n;i++)
	{
		if(vis[i] == false)
		{
			k = i;
			break;
		}
	}
	root = createTree(k);
	if(isCompleteBinaryTree(root))
	{
		printf("YES %d\n",result->data);
	}
	else
	{
		printf("NO %d\n",root->data);
	}
	return 0;
}