feat: add kotlin solutions to lc problems (doocs#3492)

Author: Zuoqiu-Yingyi

solution/0000-0099/0001.Two Sum/README.md

@@ -318,6 +318,25 @@ proc twoSum(nums: seq[int], target: int): seq[int] =
   return @[]
 ```
 
+#### Kotlin
+
+```kotlin
+class Solution {
+    fun twoSum(nums: IntArray, target: Int): IntArray {
+        val m = mutableMapOf<Int, Int>()
+        nums.forEachIndexed { i, x ->
+            val y = target - x
+            val j = m.get(y)
+            if (j != null) {
+                return intArrayOf(j, i)
+            }
+            m[x] = i
+        }
+        return intArrayOf()
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

solution/0000-0099/0001.Two Sum/README_EN.md

@@ -315,6 +315,25 @@ proc twoSum(nums: seq[int], target: int): seq[int] =
   return @[]
 ```
 
+#### Kotlin
+
+```kotlin
+class Solution {
+    fun twoSum(nums: IntArray, target: Int): IntArray {
+        val m = mutableMapOf<Int, Int>()
+        nums.forEachIndexed { i, x ->
+            val y = target - x
+            val j = m.get(y)
+            if (j != null) {
+                return intArrayOf(j, i)
+            }
+            m[x] = i
+        }
+        return intArrayOf()
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->