pat 1110. Complete Binary Tree (25)

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

두 갈래 나무가 완전 두 갈래 나무인지 아닌지 판단하기:
층차적으로 훑어볼 때 방문한 결점의 수를 기록하고 이 결점이 아이의 결점이 없을 때 훑어보는 것을 끝내고 방문한 노드의 수가 n이 아닐 때 완전한 두 갈래 나무가 아니다.
주의: n<20, 10보다 작은 것이 아니라 문자를 숫자로 바꿔야 합니다.
#include
#include
#include
using namespace std;
#include
#include
#include
#define MS(a,b) memset(a,b,sizeof(a))
int last,n,cnt;
vectorv;
struct node
{
    int left,right,fa;
}tree[200];
void bfs(int root)
{
    int rt;
    queueq;
    q.push(root);
    while(!q.empty())
    {
      rt=q.front();
      q.pop();
     if(rt!=-1)
     {
        last=rt;// 。
        cnt++;// 。
     }
       if(rt==-1)break;
        q.push(tree[rt].left);
        q.push(tree[rt].right);
    }
}
int main()
{
    /*#ifndef ONLINE_JUDGE
    freopen("in.txt","r",stdin);
    freopen("out.txt","w",stdout);
    #endif*/
    int i;
    char s1[5],s2[5];
    scanf("%d",&n);
    for(i=0;i>s1>>s2;
       if(s1[0]!='-')
         {  sscanf(s1,"%d",&tree[i].left);// 。
            tree[tree[i].left].fa=i;
         }
       else tree[i].left=-1;
       if(s2[0]!='-')
         {  sscanf(s2,"%d",&tree[i].right);
            tree[tree[i].right].fa=i;
         }
       else tree[i].right=-1;
   }
   int root=-1;
   for(i=0;i

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