add 965

fishercoder1534 · fishercoder1534 · commit 0655edab7e07 · 2018-12-31T17:33:04.000-08:00
diff --git a/README.md b/README.md
@@ -29,6 +29,7 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|---------------|---------------|--------|-------------|-------------
+|965|[Univalued Binary Tree](https://leetcode.com/problems/univalued-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_965.java) | O(n) | O(h) | |Easy| DFS, recursion
 |961|[N-Repeated Element in Size 2N Array](https://leetcode.com/problems/n-repeated-element-in-size-2n-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_961.java) | O(n) | O(1) | |Easy|
 |944|[Delete Columns to Make Sorted](https://leetcode.com/problems/delete-columns-to-make-sorted/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_944.java) | O(n) | O(1) | |Easy|
 |941|[Valid Mountain Array](https://leetcode.com/problems/valid-mountain-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_941.java) | O(n) | O(1) | |Easy|
diff --git a/src/main/java/com/fishercoder/solutions/_965.java b/src/main/java/com/fishercoder/solutions/_965.java
@@ -0,0 +1,59 @@
+package com.fishercoder.solutions;
+
+import com.fishercoder.common.classes.TreeNode;
+
+/**
+ * 965. Univalued Binary Tree
+ *
+ * A binary tree is univalued if every node in the tree has the same value.
+ *
+ * Return true if and only if the given tree is univalued.
+ *
+ * Example 1:
+ *
+ *         1
+ *        / \
+ *       1   1
+ *      / \   \
+ *     1  1   1
+ *
+ * Input: [1,1,1,1,1,null,1]
+ * Output: true
+ *
+ *
+ * Example 2:
+ *        2
+ *       / \
+ *      2   2
+ *     / \
+ *    5  2
+ *
+ * Input: [2,2,2,5,2]
+ * Output: false
+ *
+ *
+ * Note:
+ *
+ * The number of nodes in the given tree will be in the range [1, 100].
+ * Each node's value will be an integer in the range [0, 99].
+ */
+public class _965 {
+  public static class Solution1 {
+    public boolean isUnivalTree(TreeNode root) {
+      if (root == null) {
+        return true;
+      }
+      return dfs(root, root.val);
+    }
+
+    private boolean dfs(TreeNode root, int value) {
+      if (root == null) {
+        return true;
+      }
+      if (root.val != value) {
+        return false;
+      }
+      return dfs(root.left, value) && dfs(root.right, value);
+    }
+  }
+}
diff --git a/src/test/java/com/fishercoder/_965Test.java b/src/test/java/com/fishercoder/_965Test.java
@@ -0,0 +1,34 @@
+package com.fishercoder;
+
+import com.fishercoder.common.classes.TreeNode;
+import com.fishercoder.common.utils.TreeUtils;
+import com.fishercoder.solutions._14;
+import com.fishercoder.solutions._965;
+import java.util.Arrays;
+import java.util.List;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _965Test {
+  private static _965.Solution1 solution1;
+  private static TreeNode root;
+
+  @BeforeClass
+  public static void setup() {
+    solution1 = new _965.Solution1();
+  }
+
+  @Test
+  public void test1() {
+    root = TreeUtils.constructBinaryTree(Arrays.asList(1, 1, 1, 1, 1, null, 1));
+    assertEquals(true, solution1.isUnivalTree(root));
+  }
+
+  @Test
+  public void test2() {
+    root = TreeUtils.constructBinaryTree(Arrays.asList(2, 2, 2, 5, 2));
+    assertEquals(false, solution1.isUnivalTree(root));
+  }
+}
