kt: add «1072. Flip Columns For Maximum Number of Equal Rows»

URL:	https://leetcode.com/problems/flip-columns-for-maximum-number-of-equal-rows/
Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/flip-columns-for-maximum-number-of-equal-rows.kt

@@ -0,0 +1,18 @@
+class Solution {
+    fun maxEqualRowsAfterFlips(matrix: Array<IntArray>): Int {
+        val freqs = mutableMapOf<String, Int>()
+
+        matrix
+            .map { row ->
+                row.map { it == row[0] }.joinToString(separator = "")
+            }
+            .forEach { pattern ->
+                freqs.put(
+                    pattern,
+                    1 + freqs.getOrDefault(pattern, 0),
+                )
+            }
+
+        return freqs.values.max()
+    }
+}