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community.topcoder.com/tc?module=Static&d1=tutorials&d2=lowestCommonAncestor
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Node *FindLCA(Node *root, Node *first, Node *second)
{
  if(root==NULL)
    return NULL;
  if( (root == first) || (root == second) )
    return root;
  Node *L = findLCA(root->left, first, second);
  Node *R = findLCA(root->right, first, second);
  if ( L && R )
    return root;
  else if (L)
    return L;
  else if (R)
    return R;
}

int lca(Node *Root, int n1, int n2){
    int found = 0;
    if(Root == NULL) return 0;
    if(Root->data == n1 || Root->data == n2)
                  return 1+lca(Root->left, n1,n2)+lca(Root->right, n1,n2);
    found = lca(Root->left, n1,n2)+lca(Root->right, n1,n2);
    if(found == 2){
             printf("\n%d\n", Root->data);
             return 0;
    }
    return found;
}

int data1;
int data2;
node* LCS(node *root, bool *firstfound, bool *secondfound)
{
if(root == null ) return null;
node *left = LCS(root->left, firstfound, secondfound);
node *right = LCS(root->right, firstfound, secondfound);
if(left > 0 || right > 0)
{
return(left > 0 ? left : right);
}
if(left < 0 && right < 0)
{
return root;
}
else if (left <0 || right < 0)
{
if(firstfound && root->data==data2)
{
return root;
}
else if(secondfound && root->data == data1
{
return root;
}
else
{
return -1000;
}
}
else
{
if(root->data == data1)
{
*firstfound = true;
return -1000;
}
else if (root->data == data2)
{
*secondfound = true;
return -1000;
}
}
return null;
}