pat-a1110. Complete Binary Tree (25)

这个题西先是没好好读题，没注意到no后面要输出根节点。。

然后是写太快了没注意范围，以为节点编号都是个位数。这个点错了我好多。。

#include<cstdio>#include<map>#include<vector>#include<queue>#include<cstring>using namespace std;map<int,vector<int> >tree;int p[50];int last;bool bfs(int root){queue<int> q;int flag=1;q.push(root);while(!q.empty()){int t=q.front();q.pop();if(flag==1&&t==-1){flag=0;}if(flag==0&&t!=-1) return 0;if(t!=-1){last=t;q.push(tree[t][0]);q.push(tree[t][1]);}}return 1;}int fun(char* s){int ans=0;int len=strlen(s);for(int i=0;i<len;++i) ans=ans*10+s[i]-'0';return ans;}int main(){int n;scanf("%d",&n);char a[2],b[2];for(int i=0;i<n;++i){scanf("%s%s",a,b);int x=0;if(a[0]!='-') x=fun(a);else x=-1;if(x!=-1) p[x]=1;tree[i].push_back(x);if(b[0]!='-') x=fun(b);else x=-1;tree[i].push_back(x);if(x!=-1) p[x]=1;}int root=-1;for(int i=0;i<n;++i){if(p[i]==0){root=i;break;}}if(bfs(root)) printf("YES %d\n",last);else printf("NO %d\n",root);return 0;}

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:

97 8- -- -- -0 12 34 5- -- -

Sample Output 1:

YES 8

Sample Input 2:

8- -4 50 6- -2 3- 7- -- -

Sample Output 2:

NO 1