leetcode上的题目

1. 数组a[i], 求数组output，其中output[i]=product(a[j] | j!=i) 

void f(int *a, int *output, int n)
{
  for(int i=0;i<n;i++)
{
  output[i] = 1;  
}  

int left = 1, right = 1;
for(int i=0;i<n;i++)
{
  output[i] *= left;
  output[n-1-i] *= right;
  left *= a[i];
  right *= a[n-1-i];  
}
}

2. 非递归遍历二叉树

void inorder(node* root)
{
   stack<node*> s;
   node *current = root;
   while(!s.empty()||current)
   {
       if(current)
       {
            s.push(current);
            current = current->left;
        }
        else
        {
              current = s.top();
              s.pop();
              cout<<current->data<<endl;
              current = current->right;
         }
   }
}