257.bindary tree paths

Author: jackzhenguo

Tree/Tree.TreeLib/TreePaths.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Tree.TreeLib
+{
+    public class TreePaths
+    {
+            //Given a binary tree, return all root-to-leaf paths.
+            //For example, given the following binary tree:
+            //   1
+            // /   \
+            //2     3
+            // \
+            //  5
+            //All root-to-leaf paths are:
+            //["1->2->5", "1->3"]
+        public IList<string> BinaryTreePaths(TreeNode root)
+        {
+            if (root == null)
+                return new List<string>();
+            if (root.left == null && root.right == null)
+                return new List<string> { root.val.ToString() };
+            IList<string> rtn = new List<string>();
+            IList<string> rtnleft =  BinaryTreePaths(root.left);//左子树路径
+            foreach(var item in rtnleft)//左子树都继承于根节点
+                rtn.Add(root.val + "->" + item);
+            IList<string> rtnright = BinaryTreePaths(root.right);
+            foreach (var item in rtnright)
+                rtn.Add(root.val + "->" + item);
+            return rtn;
+        }
+    }
+}