add 814

Author: fishercoder1534

README.md

@@ -95,6 +95,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |824|[Goat Latin](https://leetcode.com/problems/goat-latin/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_824.java) | O(n) | O(1) | |Easy| 
 |821|[Shortest Distance to a Character](https://leetcode.com/problems/shortest-distance-to-a-character/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_821.java) | O(n) | O(k) (k is the number of char C in S) | |Easy| 
 |819|[Most Common Word](https://leetcode.com/problems/most-common-word/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_819.java) | O(m+n) | O(n) | |Easy| HashMap
+|814|[Binary Tree Pruning](https://leetcode.com/problems/binary-tree-pruning/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_814.java) | O(n) | O(n) | |Medium| recursion, DFS 
 |811|[Subdomain Visit Count](https://leetcode.com/problems/subdomain-visit-count/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_811.java) | O(n) | O(n) | |Easy| HashMap
 |806|[Number of Lines To Write String](https://leetcode.com/problems/number-of-lines-to-write-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_806.java) | O(n) | O(1) | |Easy|
 |804|[Unique Morse Code Words](https://leetcode.com/problems/unique-morse-code-words/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_804.java) | O(S) | O(S) | |Easy|

src/main/java/com/fishercoder/solutions/_814.java

@@ -0,0 +1,66 @@
+package com.fishercoder.solutions;
+
+import com.fishercoder.common.classes.TreeNode;
+
+/**
+ * 814. Binary Tree Pruning
+ *
+ * We are given the head node root of a binary tree, where additionally every node's value is either a 0 or a 1.
+ * Return the same tree where every subtree (of the given tree) not containing a 1 has been removed.
+ * (Recall that the subtree of a node X is X, plus every node that is a descendant of X.)
+ *
+ * Example 1:
+ * Input: [1,null,0,0,1]
+ * Output: [1,null,0,null,1]
+ * Explanation:
+ * Only the red nodes satisfy the property "every subtree not containing a 1".
+ * The diagram on the right represents the answer.
+ * 1                              1
+ *  \                              \
+ *   0             ---->            0
+ *  / \                              \
+ * 0   1                              1
+ *
+ *
+ * Example 2:
+ * Input: [1,0,1,0,0,0,1]
+ * Output: [1,null,1,null,1]
+ *              1                 1
+ *             / \                 \
+ *            0   1    ---->        1
+ *           / \  / \                \
+ *          0  0 0  1                1
+ *
+ *
+ * Example 3:
+ * Input: [1,1,0,1,1,0,1,0]
+ * Output: [1,1,0,1,1,null,1]
+ *               1                      1
+ *              / \                    / \
+ *             1   0     ----->       1  0
+ *            / \ / \                / \  \
+ *           1  1 0 1               1  1   1
+ *          /
+ *         0
+ *
+ *
+ * Note:
+ *
+ * The binary tree will have at most 100 nodes.
+ * The value of each node will only be 0 or 1.*/
+public class _814 {
+    public static class Solution1 {
+        /**credit: https://leetcode.com/problems/binary-tree-pruning/discuss/122730/C%2B%2BJavaPython-Self-Explaining-Solution-and-2-lines*/
+        public TreeNode pruneTree(TreeNode root) {
+            if (root == null) {
+                return root;
+            }
+            root.left = pruneTree(root.left);
+            root.right = pruneTree(root.right);
+            if (root.left == null && root.right == null && root.val == 0) {
+                return null;
+            }
+            return root;
+        }
+    }
+}