树2——List Leaves

最新推荐文章于 2024-06-07 05:14:20 发布

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最新推荐文章于 2024-06-07 05:14:20 发布

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本文介绍了一种使用队列实现的层序遍历算法，该算法用于在一棵树中按从上到下、从左到右的顺序列出所有的叶子节点。通过输入树的结构，算法能够准确地找到并打印出所有叶子节点的索引。

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Given a tree, you are supposed to list all the leaves in the order of top down, and left to right.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer $N$ ( $≤10\le 10$ ) 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 test case, print in one line all the leaves' indices in the order of top down, and left to right. There must be exactly one space between any adjacent numbers, and no extra space at the end of the line.

Sample Input:

8
1 -
- -
0 -
2 7
- -
- -
5 -
4 6

Sample Output:

4 1 5

用队列实现层序遍历

#include <stdio.h>


#define MaxTree 10
#define Null -1


typedef int Tree ;
typedef int  ElementType ;
typedef struct TreeNode TreeNodeArray ;


struct TreeNode
{
    ElementType Element ;
    Tree Left ;
    Tree Right ;
} ;
struct TreeNode Tree1[MaxTree];
TreeNode node[MaxTree];
TreeNode Queue[MaxTree];
int first = -1, last = -1,N;
Tree BuildeTree( TreeNodeArray Tree[]  )
{
    int i,check[MaxTree] ;
    char cl,cr ;
    int Root ;
    scanf("%d",&N ) ;

    if( N!=0 )
    {
        for( i=0 ; i<N ; i++ ) check[i] = 0 ;
        for( i=0 ; i<N ; i++ )
        {
            scanf("  %c %c" ,  &cl , &cr ) ;
            Tree[i].Element=i;
            if( cl != '-' )
            {
                Tree[i].Left = cl-'0' ;
                check[ Tree[i].Left ] = 1 ;
            }
            else Tree[i].Left = Null ;

            if( cr!= '-' )
             {
                 Tree[i].Right = cr-'0' ;
                 check[ Tree[i].Right ] =1 ;
             }
            else Tree[i].Right =  Null ;
        }
    }
    else
        return  Null ;

    for(i=0 ; i<N ; i++ )
    {
        if(check[ i ]==0 )
        break ;
    }
    Root = i ;

    return  Root ;
}
void Push(TreeNode treeNode)
{
    Queue[++last] = treeNode;
}

TreeNode Pop()
{
    return Queue[++first];
}


void printLeaves(int root, int n)
{
    int leaves[MaxTree];
    int k = 0;
    Push(node[root]);
    for (int i = 0; i < n; i++)
    {
        TreeNode tn = Pop();
        if (tn.Left == -1 && tn.Right == -1)
            leaves[k++] = tn.Element;
        if (tn.Left != -1)
            Push(node[tn.Left]);
        if (tn.Right != -1)
            Push(node[tn.Right]);
    }
    for (int i = 0; i < k-1; i++)
        printf("%d ", leaves[i]);
    printf("%d\n", leaves[k-1]);
}

int main(  )
{
    Tree Root;
    Root = BuildeTree( node ) ;
    printLeaves(Root, N);
    return 0 ;

}