add solution for leetcode 110

Author: Zhanganjin0520

README.md

@@ -301,7 +301,7 @@ LeetCode
 |114|[Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list/)| |Medium|
 |113|[Path Sum II](https://leetcode.com/problems/path-sum-ii/)| |Medium|
 |112|[Path Sum](https://leetcode.com/problems/path-sum/)| |Easy|
-|111|[Minimum Depth of Binary Tree](https://leetcode.com/problems/minimum-depth-of-binary-tree/)| |Easy|
+|111|[Minimum Depth of Binary Tree](https://leetcode.com/problems/minimum-depth-of-binary-tree/)| [java](./algorithms/balancedBinaryTree/Solution.java) |Easy|
 |110|[Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree/)| |Easy|
 |109|[Convert Sorted List to Binary Search Tree](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/)| |Medium|
 |108|[Convert Sorted Array to Binary Search Tree](https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/)| |Medium|

algorithms/balancedBinaryTree/Solution.java

@@ -0,0 +1,31 @@
+class Solution {
+
+    // 自上而下而下递归思路，比较左树与右树高度差
+    public boolean isBalanced(TreeNode root) {
+        if (null == root) {
+            return true;
+        }
+        int leftDepth = recrusionTreeDepth(root.left, 0);
+        int rightDepth = recrusionTreeDepth(root.right, 0);
+        return Math.abs(leftDepth - rightDepth) <= 1 && isBalanced(root.left) && isBalanced(root.right);
+    }
+
+    private int recrusionTreeDepth(TreeNode node, int depth) {
+        if (node == null) {
+            return depth;
+        }
+        depth++;
+        int leftDepth = recrusionTreeDepth(node.left, depth);
+        int rightDepth = recrusionTreeDepth(node.right, depth);
+        return Math.max(leftDepth, rightDepth);
+    }
+
+    //官方给出的计算树的高度的方法
+    public int height(TreeNode root) {
+        if (root == null) {
+            return 0;
+        } else {
+            return Math.max(height(root.left), height(root.right)) + 1;
+        }
+    }
+}