BinaryTreePaths.java

src/BinaryTreePaths.java

@@ -0,0 +1,50 @@
+package Tree;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * 
+ * @author chenqun
+ * Given a binary tree, return all root-to-leaf paths.
+ *
+ */
+public class BinaryTreePaths {
+	List<List<Integer>> ans  = new ArrayList<List<Integer>>();
+	List<String> ret  = new ArrayList<String>();
+	public List<String> binaryTreePaths(TreeNode root){
+		List<Integer> list = new ArrayList<Integer>();
+		if(root == null) return ret;
+		dfs(root,list);
+		for(int i=0; i<ans.size(); i++){
+			String path = "";
+			int length = ans.get(i).size();
+			path = path + ans.get(i).get(0);
+			for(int j=1; j<length;j++)
+				path = path + "->" + ans.get(i).get(j);
+
+			ret.add(path);
+		}
+		return ret;
+	}
+	public void dfs(TreeNode root,List<Integer> list){
+		list.add(root.val);
+		if(root.left == null && root.right == null){
+			ans.add(new ArrayList(list));
+			list.remove(list.size()-1);
+			return;
+		}
+		if(root.left != null){
+			dfs(root.left,list);
+		}
+		if(root.right != null){
+			dfs(root.right,list);
+		}
+		list.remove(list.size()-1);
+	}
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+
+	}
+
+}