update 590

fishercoder1534 · fishercoder1534 · commit 002f88ca4893 · 2024-08-25T18:55:25.000-07:00
diff --git a/src/main/java/com/fishercoder/solutions/firstthousand/_590.java b/src/main/java/com/fishercoder/solutions/firstthousand/_590.java
@@ -8,25 +8,18 @@
 public class _590 {
     public static class Solution1 {
         public List<Integer> postorder(Node root) {
-            List<Integer> result = new ArrayList<>();
-            if (root == null) {
-                return result;
-            }
-            dfs(root, result);
-            result.add(root.val);
-            return result;
+            return post(root, new ArrayList<>());
         }
 
-        private void dfs(Node root, List<Integer> result) {
+        private List<Integer> post(Node root, List<Integer> list) {
             if (root == null) {
-                return;
+                return list;
             }
-            if (root.children.size() > 0) {
-                for (Node child : root.children) {
-                    dfs(child, result);
-                    result.add(child.val);
-                }
+            for (Node child : root.children) {
+                post(child, list);
             }
+            list.add(root.val);
+            return list;
         }
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -8,25 +8,18 @@`
`8`	`8`	`public class _590 {`
`9`	`9`	`public static class Solution1 {`
`10`	`10`	`public List<Integer> postorder(Node root) {`
`11`		`- List<Integer> result = new ArrayList<>();`
`12`		`- if (root == null) {`
`13`		`- return result;`
`14`		`- }`
`15`		`- dfs(root, result);`
`16`		`- result.add(root.val);`
`17`		`- return result;`
	`11`	`+ return post(root, new ArrayList<>());`
`18`	`12`	`}`
`19`	`13`
`20`		`- private void dfs(Node root, List<Integer> result) {`
	`14`	`+ private List<Integer> post(Node root, List<Integer> list) {`
`21`	`15`	`if (root == null) {`
`22`		`- return;`
	`16`	`+ return list;`
`23`	`17`	`}`
`24`		`- if (root.children.size() > 0) {`
`25`		`- for (Node child : root.children) {`
`26`		`- dfs(child, result);`
`27`		`- result.add(child.val);`
`28`		`- }`
	`18`	`+ for (Node child : root.children) {`
	`19`	`+ post(child, list);`
`29`	`20`	`}`
	`21`	`+ list.add(root.val);`
	`22`	`+ return list;`
`30`	`23`	`}`
`31`	`24`	`}`
`32`	`25`	`}`