你好 我正在嘗試實現 hasPathSum（） 對於給定數字的意思是在根到葉節點之間存在任何路徑。

我從斯坦福網站上獲得了這段代碼。我認為這是錯誤的

/** 
 Given a tree and a sum, returns true if there is a path from the root 
 down to a leaf, such that adding up all the values along the path 
 equals the given sum. 
 Strategy: subtract the node value from the sum when recurring down, 
 and check to see if the sum is 0 when you run out of tree. 
*/ 

boolean hasPathSum(Node node, int sum) { 
 //return true if we run out of tree and sum==0 
  if (node == null){ 
    return(sum == 0); 
  } 
  else { 
 //otherwise check both subtrees 
    int subSum = sum - node.data; 
    return(hasPathSum(node.left, subSum) || hasPathSum(node.right, subSum)); 
  } 

這是正確的實施嗎？

我想這如果應該是

• if(node.left==null && node.right==null)

如果我錯了請清除我的困惑

考慮這種情況：

          5
        /\
        2   1
      /   
      3

-謝謝