LeetCode-Easy刷題(26) Path Sum
阿新 • • 發佈:2018-12-04
Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
For example:Given the below binary tree and
sum = 22
,
5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1
return true, as there exist a root-to-leaf path 5->4->11->2
which sum is 22.
判斷是否存在從根節點到葉子節點的值相加結果為給定的值,存在返回true,否則false;
//深度優先 維護要完成的剩餘目標值 public boolean hasPathSum(TreeNode root, int sum) { if(root ==null){//以最後空接點作為遞迴結束 return false; } //滿足題意的結束條件 if(root.left ==null && root.right ==null && root.val == sum){ return true; } return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val) ; }