二叉树的最低公共祖先（剑指offer）

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <list>
using namespace std;
#define M 2002*2
typedef struct Tree
{
    int data;
    struct Tree *lson,*rson;
} Tnode,*ListTree;

int cnt;
ListTree a,b;
int n,m;

int* init(char *str,int &s)
{
    int* strn=(int *)malloc(sizeof(int)*M);
    int len=strlen(str);
    int tmp=0;
    int k=0;
    str[len]=' ';
    len++;
    for(int i=0; i<len; i++)
    {
        if(str[i]==' ')
        {
            strn[k++]=tmp;
            //cout<<tmp<<' ';
            tmp=0;
        }
        else
        {
            tmp=tmp*10+str[i]-'0';
        }
    }
    s=k;
    return strn;
}

ListTree built(int *arr)
{
    ListTree list;

    if(arr[cnt++]==0)
        list=NULL;
    else
    {
        list=(ListTree)malloc(sizeof(Tnode));
        list->data=arr[cnt-1];
        if(n==arr[cnt-1])
            a=list;
        if(m==arr[cnt-1])
            b=list;
        list->lson=built(arr);
        list->rson=built(arr);

    }
    return list;
}

bool getPath(ListTree root,ListTree node,list<ListTree>&path)
{
    if(root==NULL)
        return false;
    if(root==node)
        return true;
    path.push_back(root);
    bool found=false;
    found=getPath(root->lson,node,path);
    if(!found)
    {
        found=getPath(root->rson,node,path);
    }
    if(!found)
        path.pop_back();
    return found;
}

ListTree getComm(list<ListTree>path1,list<ListTree>path2)
{
    list<ListTree>::const_iterator it1=path1.begin();
    list<ListTree>::const_iterator it2=path2.begin();
    ListTree ans=NULL;
    while(it1!=path1.end()&&it2!=path2.end())
    {
        if(*it1==*it2)
            ans=*it1;
        it1++;
        it2++;
    }
    return ans;
}

ListTree getLastNode(ListTree root,ListTree ra,ListTree rb)
{
    if(root==NULL||ra==NULL ||rb==NULL)
        return NULL;
    list<ListTree>path1,path2;
    path1.clear();
    path2.clear();
    bool f1=getPath(root,ra,path1);
    bool f2=getPath(root,rb,path2);
    if(f1&&f2)
    {
        return getComm(path1,path2);
    }
    else
        return NULL ;
}


void output(ListTree root)
{
    if(root==NULL)
        return ;
    cout<<root->data<<" ";
    output(root->lson);
    output(root->rson);
    return ;
}

int main()
{
    int cas;
    scanf("%d",&cas);
    getchar();

    while(cas--)
    {
        char *str=(char *)malloc(sizeof(char)*M);
        gets(str);
        int k;
        scanf("%d %d",&n,&m);
        int *p=init(str,k);
        cnt=0;
        ListTree mytree=built(p);
        ListTree ans=getLastNode(mytree,a,b);
        if(ans!=NULL)
            printf("%d\n",ans->data);
        else
            printf("My God\n");
        getchar();
    }
    return 0;
}