使用C语言求二叉树结点的最低公共祖先的方法

struct BinaryNode
{
 char value;
 BinaryNode *left;
 BinaryNode *right;
};

bool GetNodePath(BinaryNode *pRoot,BinaryNode *pNode,vector<BinaryNode*> &v)
{
 if(pRoot==NULL)
  return false;
 v.push_back(pRoot);
 if(pRoot==pNode)
  return true;
 bool found=GetNodePath(pRoot->left,pNode,v);
 if(!found)
  found=GetNodePath(pRoot->right,pNode,v);
 if(!found)
  v.pop_back();
}

BinaryNode* GetCommonParent(BinaryNode *pRoot,BinaryNode *pNode1,BinaryNode *pNode2)
{
 if(pRoot==NULL || pNode1==NULL || pNode2==NULL)
  return NULL;
 vector<BinaryNode*> v1,v2;
 GetNodePath(pRoot,pNode1,v1);
 GetNodePath(pRoot,pNode2,v2);
 BinaryNode *pLast=pRoot;
 vector<BinaryNode*>::iterator ite1=v1.begin();
 vector<BinaryNode*>::iterator ite2=v2.begin();
 while(ite1!=v1.end() && ite2!=v2.end())
 {
  if(*ite1==*ite2)
   pLast=*ite1;
  ite1++;
  ite2++;
 }
 return pLast;
}

  #include <stdio.h> 
  #include <stdlib.h> 
    
  #define N 7000 
    
  typedef struct btree { 
    struct btree *lchild, *rchild; 
    int data; 
  } btree; 
    
  typedef struct stack { 
    int top; 
    btree* data[N]; 
  } stack; 
    
  stack *first, *second; 
  int oneflag, secflag; 
    
  /** 
   * 根据前序序列递归构建二叉树 
   */ 
  void createBtree(btree **t) 
  { 
    int data; 
    scanf("%d", &data); 
    
    if (data == 0) { 
      *t = NULL; 
    } else { 
      *t = (btree *)malloc(sizeof(btree)); 
      (*t)->data = data; 
      createBtree(&(*t)->lchild); 
      createBtree(&(*t)->rchild); 
    } 
  } 
    
  /** 
   * 后序遍历二叉树,构造遍历栈 
   */ 
  void postTraverse(btree *t, stack *s, int srcnum, int *flag) 
  { 
    if (t != NULL) { 
      btree *pre; 
      pre = NULL; 
    
      s->data[s->top ++] = t; 
      while (s->top > 0 || t) { 
        if (t) { 
          s->data[s->top ++] = t; 
          if (t->data == srcnum) { 
            *flag = 1; 
            break; 
          } 
          t = t->lchild; 
        } else { 
          t = s->data[-- s->top]; 
          if (t->rchild == NULL || t->rchild == pre) { 
            pre = t; 
            t = NULL; 
          } else { 
            s->data[s->top ++] = t; 
            t = t->rchild; 
          } 
        } 
      } 
    } 
  } 
    
  /** 
   * 查找两个栈第一个公共元素 
   * 
   * T = O(n) 
   * 
   */ 
  void stackCommonData(stack *f, stack *s) 
  { 
    int top, data, flag; 
    
    top = (f->top > s->top) ? s->top : f->top; 
    
    while (top > 0) { 
      if (f->data[top - 1]->data == s->data[top - 1]->data) { 
        data = f->data[top - 1]->data; 
        flag = 1; 
        break; 
      } else { 
        top --; 
      } 
    } 
    
    if (flag) { 
      printf("%d\n", data); 
    } else { 
      printf("My God\n"); 
    } 
  } 
    
  /** 
   * 清理二叉树 
   * 
   */ 
  void cleanBtree(btree *t) 
  { 
    if (t) { 
      cleanBtree(t->lchild); 
      cleanBtree(t->rchild); 
      free(t); 
    } 
  } 
    
    
  int main(void) 
  { 
    int n, sf, se; 
    btree *t; 
    
    scanf("%d", &n); 
    while (n --) { 
      createBtree(&t); 
      scanf("%d %d", &sf, &se); 
        
      first = (stack *)malloc(sizeof(stack)); 
      first->top = 0; 
      oneflag = 0; 
      postTraverse(t, first, sf, &oneflag); 
    
      second = (stack *)malloc(sizeof(stack)); 
      second->top = 0; 
      secflag = 0; 
      postTraverse(t, second, se, &secflag); 
    
      if (oneflag == 0 || secflag == 0 || first->top == 0 || second->top == 0) { 
        printf("My God\n"); 
        cleanBtree(t); 
        continue; 
      } else { 
        stackCommonData(first, second); 
        cleanBtree(t); 
      } 
    } 
    return 0; 
  }