最近公共祖先

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define N 200
#define M 200
struct Node
{
    char a[N];
    int numChild;
    struct Node *father;
    struct Node *child[N];       
};
struct Node* searchFather(struct Node *ancient,char father[])
{
    int i;
    int num=ancient->numChild;
    struct Node *p;
    if(0==strcmp(ancient->a,father))
    {
        return ancient;                         
    }
    else
    {
        for(i=0;i<num;i++)
        {
            p=searchFather(ancient->child[i],father);   
            if(p!=NULL)
                return p;
        } 
    }
    return NULL;       
}
int insertNode(struct Node *ancient[],int* numAncient,char father[],char child[])
{
    struct Node *p=NULL,*temp;
    int i;
    for(i=0;i<*numAncient;i++)
    {
        p=searchFather(ancient[i],father);
        if(p!=NULL)
            break;        
    }
    temp=(struct Node*)malloc(sizeof(struct Node));
    if(NULL==temp)
    {
        perror("failed");
        exit(-1);              
    }
    memset(temp,0,sizeof(struct Node));
    if(NULL==p)//如果父节点不存在则先插入父节点 
    {
        ancient[(*numAncient)++]=temp;
        strcpy(temp->a,father);
        return 0;
    }
    else
    {
        p->child[p->numChild++]=temp;
        temp->father=p;    
        strcpy(temp->a,child);   
    }
    return 1;      
}
void searchSameAncient(struct Node *ancient[],int numAncient,char father[],char child[])
{
    struct Node *pf,*pc; 
    char a[M][N],b[M][N];
    int i,ia,ib,flag;
    ia=ib=flag=0;
    pf=pc=NULL;
    for(i=0;i<numAncient;i++)
    {
        pf=searchFather(ancient[i],father);
        if(pf!=NULL)
            break;        
    }
    if(pf!=NULL)
    {
        strcpy(a[ia++],pf->a);
        while(pf->father!=NULL)
        {
            pf=pf->father;
            strcpy(a[ia++],pf->a);
        }           
    }
    for(i=0;i<numAncient;i++)
    {
        pc=searchFather(ancient[i],child);
        if(pc!=NULL)
            break;        
    }
    if(pc!=NULL)
    {
        strcpy(b[ib++],pc->a);
        while(pc->father!=NULL)
        {
            pc=pc->father;
            strcpy(b[ib++],pc->a);
        }           
    }
    ia--;
    ib--;
    while(ia>=0 && ib>=0 && 0==strcmp(a[ia],b[ib]))
    {
        ia--;
        ib--;
        flag=1;                             
    }
    if(NULL==pf || NULL==pc)
    {
        printf("-1\n");
        return;            
    }
    else if(flag)
        printf("%s\n",a[ia+1]);
    else 
        printf("-1\n");     
}
int main()
{
    int i,n,numAncient;
    char father[N],child[N];
    struct Node *ancient[M],*p;
    memset(ancient,0,sizeof(ancient));
    numAncient=0;
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
        scanf("%s %s",father,child);
        if(0==insertNode(ancient,&numAncient,father,child))
        {
            insertNode(ancient,&numAncient,father,child);                                                   
        }
    }
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
        scanf("%s %s",father,child);
        if(0==strcmp(father,child))
            printf("%s",father);
        else
            searchSameAncient(ancient,numAncient,father,child);                
    }
    
    system("pause");
    return 0;    
}