112. 路径总和 - 力扣（LeetCode） (leetcode-cn.com)

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