kt: add «1780. Check if Number is a Sum of Powers of Three»

URL:	https://leetcode.com/problems/check-if-number-is-a-sum-of-powers-of-three/
Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/check-if-number-is-a-sum-of-powers-of-three.kt

@@ -0,0 +1,15 @@
+class Solution {
+    fun checkPowersOfThree(n: Int): Boolean {
+        var n = n
+
+        while (n > 0) {
+            if (n % 3 > 1) {
+                return false
+            }
+
+            n /= 3
+        }
+
+        return true
+    }
+}