112. Path Sum

class Solution {
    public boolean hasPathSum(TreeNode root, int targetSum) {
        if (root ==null) return false;
        if (root.left==null && root.right==null){
            return targetSum==root.val;
        }
        int nextSum = targetSum-root.val;
        return hasPathSum(root.left, nextSum) || hasPathSum(root.right, nextSum);
    }
}