Added 2 solutions

varunu28 · varunu28 · commit 7e5921db17d7 · 2019-12-29T11:51:22.000-08:00
diff --git a/Easy/Find N Unique Integers Sum up to Zero.java b/Easy/Find N Unique Integers Sum up to Zero.java
@@ -0,0 +1,20 @@
+class Solution {
+  public int[] sumZero(int n) {
+    int[] arr = new int[n];
+    int idx = 0;
+    int num = n / 2;
+    while (idx < n / 2) {
+      arr[idx++] = num * -1;
+      num--;
+    }
+    if (n % 2 != 0) {
+      arr[idx++] = 0;
+    }
+    num = n / 2;
+    while (idx < n) {
+      arr[idx++] = num;
+      num--;
+    }
+    return arr;
+  }
+}
diff --git a/Medium/All Elements in Two Binary Search Trees.java b/Medium/All Elements in Two Binary Search Trees.java
@@ -0,0 +1,55 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+class Solution {
+  List<Integer> ans;
+  public List<Integer> getAllElements(TreeNode root1, TreeNode root2) {
+    ans = new ArrayList<>();
+    helper(root1, root2);
+    return ans;
+  }
+  
+  private void helper(TreeNode r1, TreeNode r2) {
+    Stack<TreeNode> stack1 = new Stack<>();
+    Stack<TreeNode> stack2 = new Stack<>();
+    addToStack(stack1, r1);
+    addToStack(stack2, r2);
+    while (!stack1.isEmpty() || !stack2.isEmpty()) {
+      TreeNode popped1 = stack1.isEmpty() ? null : stack1.pop();
+      TreeNode popped2 = stack2.isEmpty() ? null : stack2.pop();
+      if (popped1 != null && popped2 != null) {
+        if (popped1.val > popped2.val) {
+          ans.add(popped2.val);
+          addToStack(stack2, popped2.right);
+          stack1.push(popped1);
+        }
+        else {
+          ans.add(popped1.val);
+          addToStack(stack1, popped1.right);
+          stack2.push(popped2);
+        }
+      }
+      else if (popped2 == null) {
+        ans.add(popped1.val);
+        addToStack(stack1, popped1.right);
+      }
+      else {
+        ans.add(popped2.val);
+        addToStack(stack2, popped2.right);
+      }
+    }
+  }
+  
+  private void addToStack(Stack<TreeNode> stack, TreeNode node) {
+    while (node != null) {
+      stack.push(node);
+      node = node.left;
+    }
+  }
+}
