Path Sum

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.

Java语言: PathSum

01 public boolean hasPathSum(TreeNode root, int sum) {
02   if(root==null)
03   {
04     return false;
05   }
06   if(root.left==null && root.right==null)
07   {
08     if(root.val==sum)
09       return true;
10     else
11       return false;
12   }
13   return hasPathSum(root.left,sum-root.val)||hasPathSum(root.right,sum-root.val);
14 }