Modified 2 solutions

varunu28 · varunu28 · commit 91c7533a24c0 · 2020-02-13T07:31:33.000-08:00
diff --git a/Easy/Binary Tree Paths.java b/Easy/Binary Tree Paths.java
@@ -8,26 +8,28 @@
  * }
  */
 class Solution {
-    public List<String> binaryTreePaths(TreeNode root) {
-        List<String> list = new ArrayList<>();
-        if (root != null) {
-            getString(root, "", list);
-        }
-        
-        return list;
+  List<String> list;
+  public List<String> binaryTreePaths(TreeNode root) {
+    list = new ArrayList<>();
+    if (root == null) {
+      return list;
     }
-    
-    public void getString(TreeNode root, String s, List<String> list) {
-        if (root.left == null && root.right == null) {
-            list.add(s + root.val);
-        }
-        
-        if (root.left != null) {
-            getString(root.left, s + root.val + "->", list);
-        }
-        
-        if (root.right != null) {
-            getString(root.right, s + root.val + "->", list);
-        }
+    helper(root, new StringBuilder());
+    return list;
+  }
+  
+  private void helper(TreeNode root, StringBuilder sb) {
+    if (root == null) {
+      return;
     }
+    if (root.left == null && root.right == null) {
+      sb.append(root.val);
+      list.add(sb.toString());
+    }
+    else {
+      sb.append(root.val).append("->");
+      helper(root.left, new StringBuilder(sb.toString()));
+      helper(root.right, new StringBuilder(sb.toString()));
+    }
+  }
 }
diff --git a/Easy/Cousins in Binary Tree.java b/Easy/Cousins in Binary Tree.java
@@ -8,49 +8,38 @@
  * }
  */
 class Solution {
-    public boolean isCousins(TreeNode root, int x, int y) {
-        if (root == null) {
-            return false;
-        }
-        
-        DetailedNode nodeX = helper(root, null, x, 0);
-        DetailedNode nodeY = helper(root, null, y, 0);
-        
-        if (nodeX == null || nodeY == null) {
-            return false;
-        }
-        
-        return nodeX.depth == nodeY.depth && nodeX.parent != nodeY.parent;
+  public boolean isCousins(TreeNode root, int x, int y) {
+    if (root == null || x == y) {
+      return true;
     }
-    
-    private DetailedNode helper(TreeNode root, TreeNode parent, int num, int depth) {
-        if (root == null) {
-            return null;
-        }
-        
-        if (root.val == num) {
-            return new DetailedNode(root, parent, depth - 1);
-        }
-        
-        DetailedNode left = helper(root.left, root, num, depth + 1);
-        DetailedNode right = helper(root.right, root, num, depth + 1);
-        
-        if (left == null) {
-            return right;
-        }
-        
-        return left;
+    ParentData p1 = new ParentData();
+    ParentData p2 = new ParentData();
+    helper(root, x, 0, null, p1);
+    helper(root, y, 0, null, p2);
+    return p1.depth == p2.depth && p1.parent != p2.parent;
+  }
+  
+  private void helper(TreeNode root, int x, int currDepth, TreeNode parent, ParentData p) {
+    if (root == null) {
+      return;
     }
-    
-    class DetailedNode {
-        public TreeNode node;
-        public TreeNode parent;
-        public int depth;
-        
-        public DetailedNode(TreeNode node, TreeNode parent, int depth) {
-            this.node = node;
-            this.parent = parent;
-            this.depth = depth;
-        }
+    if (root.val == x) {
+      p.depth = currDepth;
+      p.parent = parent;
     }
+    else {
+      helper(root.left, x, currDepth + 1, root, p);
+      helper(root.right, x, currDepth + 1, root, p);
+    }
+  }
+}
+
+class ParentData {
+  int depth;
+  TreeNode parent;
+  
+  public ParentData() {
+    this.depth = 0;
+    this.parent = null;
+  }
 }
