[数据结构与算法]给定一个二叉树，返回所有从根结点到叶子节点的路径

#给定一个二叉树，返回所有从根结点到叶子节点的路径

public class AllNodePath{
	private static class TreeNode{
	    int val;
	    TreeNode left;
	    TreeNode right;
	    public TreeNode(int val){
	      this.val=val;
	    }
	}
	
	public static void main(String[] args){
	    TreeNode root = new TreeNode(6);
	    TreeNode node11 =new TreeNode(2);
	    TreeNode node12 =new TreeNode(7);
	    TreeNode node21 =new TreeNode(1);
	    TreeNode  node22 =new TreeNode(5);
	    TreeNode  node31 =new TreeNode(3);
	    TreeNode  node42 =new TreeNode(4);
	    root.left= node11;
	    root.right= node12;
	    root11.left= node21;
	    root11.right= node22;
	    node22.left= node31;
	    node31.right= node42;
	
	    List<String> res=binaryTreePaths(root);
	    System.out.println(res); 
	}
	
	
	public static List<String> binaryTreePaths(TreeNode root){
	  LinkedList<String> res=new LinkedList<>();
	  if(root==null) return;
	
	   solve(root,"",res);
	  return res;    
	}
	
	public static void solve(TreeNode root,String cur,LinkedList<String> res){
	    if (root==null) return;
	    cur +=root.val;
	    if (root.left==null && root.right==null){
	       res.add(cur);
	    }else{
	       solve(root.left,cur+"->",res);
	       solve(root.right,cur+"->",res); 
	    }
	    
	 }
}