feat: add the solution of Path Sum(112) with kotlin.

Author: relish-wang

README.md

@@ -54,7 +54,7 @@
 | [108][108-question] | [Convert Sorted Array to Binary Search Tree][108-tips]       | [✅][108-java] |              | [✅][108-kotlin] |
 | [110][110-question] | [Balanced Binary Tree][110-tips]                             | [✅][110-java] |              | [✅][110-kotlin] |
 | [111][111-question] | [Minimum Depth of Binary Tree][111-tips]                     | [✅][111-java] |              | [✅][111-kotlin] |
-| [112][112-question] | [Path Sum][112-tips]                                         | [✅][112-java] |              |                  |
+| [112][112-question] | [Path Sum][112-tips]                                         | [✅][112-java] |              | [✅][112-kotlin] |
 | [118][118-question] | [Pascal's Triangle][118-tips]                                | [✅][118-java] |              |                  |
 | [119][119-question] | [Pascal's Triangle II][119-tips]                             | [✅][119-java] |              |                  |
 | [121][121-question] | [Best Time to Buy and Sell Stock][121-tips]                  | [✅][121-java] |              |                  |
@@ -508,4 +508,5 @@
 [108-kotlin]: ./src/_108/kotlin/Solution.kt
 [110-kotlin]: ./src/_110/kotlin/Solution.kt
 [111-kotlin]: ./src/_111/kotlin/Solution.kt
+[112-kotlin]: ./src/_112/kotlin/Solution.kt
 [771-kotlin]: ./src/_771/kotlin/Solution.kt

src/_112/kotlin/Solution.kt

@@ -0,0 +1,27 @@
+package _112.kotlin
+
+import structure.TreeNode
+
+/**
+ * @author relish
+ * @since 2018/05/02
+ *
+ * Definition for a binary tree node.
+ * class TreeNode(var `val`: Int = 0) {
+ *     var left: TreeNode? = null
+ *     var right: TreeNode? = null
+ * }
+ * [1] 1 true
+ * [] 0 false
+ */
+class Solution {
+    fun hasPathSum(root: TreeNode?, sum: Int): Boolean {
+        if (root == null) return false
+        if (root.left == null && root.right == null) return sum == root.`val`
+        return hasPathSum(root.right, sum - root.`val`) || hasPathSum(root.left, sum - root.`val`)
+    }
+}
+
+fun main(args: Array<String>) {
+    println(Solution().hasPathSum(TreeNode.createTestData("[1]"), 1))
+}

tips/112/README.md

@@ -27,7 +27,7 @@ return true, as there exist a root-to-leaf path `5->4->11->2` which sum is 22.
 
 题意是查找二叉树中是否存在从根结点到叶子的路径和为某一值，利用深搜在遇到叶子节点时判断是否满足即可。
 
-
+Java:
 ```java
 /**
  * Definition for a binary tree node.
@@ -47,6 +47,16 @@ class Solution {
 }
 ```
 
+kotlin(216ms/100.00%):
+```kotlin
+class Solution {
+    fun hasPathSum(root: TreeNode?, sum: Int): Boolean {
+        if (root == null) return false
+        if (root.left == null && root.right == null) return sum == root.`val`
+        return hasPathSum(root.right, sum - root.`val`) || hasPathSum(root.left, sum - root.`val`)
+    }
+}
+```
 
 ## 结语