找树中两个节点的最近公共祖先

/*查找a，b的最近公共祖先，root为根节点，out为最近公共祖先的指针地址*/
int  FindNCA(Node* root, Node* a, Node* b, Node** out)
{
    if ( root == null )
    {
        return  0;
    }

    if ( root == a || root == b )
    {
        return  1;
    }

    int  iLeft = find(root->left, a, b, out);
    if ( iLeft == 2 )
    {
        return  2;
    }

    int  iRight = find(root->right, a, b, out);
    if ( iRight == 2 )
    {
        return  2;
    }

    if ( iLeft + iRight == 2 )
    {
        *out == root;
    }
    return  iLeft + iRight;
}

void  main()
{
    Node* root = ...;
    Node* a = ...;
    Node* b = ...;
    Node* out = null;
    int  i = FindNCA(root, a, b, &out);
    if ( i == 2 )
    {
        printf("Result pointer is %p" , out);
    }
    else
    {
        printf("Not find pointer" );
    }
}

 #include <stdio.h>



 
 


#include <stdlib.h>
 
 

 


struct
 Node

 


{
   


const


Node


 


*


left


,


 


*


right


;



 
     


const


 


char


*


 name


;



 
     


Node


(


const


 


Node


 


*


left


,


 


const


 


Node


 


*


right


,


 


const


 


char


*


 name


)



 
         


:


left


(


left


),


 right


(


right


),


 name


(


name


)


 
 
     


{}



 
     


Node


(


const


 


char


*


 name


)



 
         


:


left


(


NULL


),


 right


(


NULL


),


 name


(


name


)


 
 
     


{}



 
 


};



 
 
 
 


const


 


Node


*


 LCA


(


const


 


Node


*


 root


,


 


const


 


Node


*


 a


,


 


const


 


Node


*


 b


)


 
 
 


{



 
     


if


(


root 


==


 a


)


 


return


 a


;



 
     


if


(


root 


==


 b


)


 


return


 b


;



 
     


if


(


root 


==


 NULL


)


 


return


 NULL


;



 
     


const


 


Node


*


 llca 


=


 LCA


(


root


->


left


,


 a


,


 b


);



 
     


const


 


Node


*


 rlca 


=


 LCA


(


root


->


left


,


 a


,


 b


);



 
     


if


(


llca 


&&


 rlca


)


 


return


 root


;


 


// 这就是我们要找的节点。



 
 
 
     


// 否则返回我们得到的不是零的节点



 
     


if


(


llca


)


 


return


 llca


;



 
     


return


 rlca


;


 
 
 


}



 
 
 
 


int


 main


()



 
 


{



 
     


Node


 


*


a


,


 


*


b


;



 
     


Node


 


*


root 


=


 


new


 


Node


(


new


 


Node


(


a 


=


 


new


 


Node


(


"a"


),


NULL


,


"b"


),


 b 


=


 


new


 


Node


(


"c"


),


"d"


);



 
     printf


(


"%s/n"


,


 LCA


(


root


,


 a


,


b


)->


name


);



 
     


return


 


0


;



 
 


}
 
 
 
 http://fayaa.com/tiku/view/160/