cs: add «3394. Check if Grid can be Cut into Sections»

URL:	https://leetcode.com/problems/check-if-grid-can-be-cut-into-sections/
Signed-off-by: Matej Focko <me@mfocko.xyz>

cs/check-if-grid-can-be-cut-into-sections.cs

@@ -0,0 +1,26 @@
+public class Solution {
+    private const int X = 0;
+    private const int Y = 1;
+
+    private bool CheckCuts(int[][] rectangles, int dimension) {
+        Array.Sort(rectangles, (x, y) =>
+            x[dimension].CompareTo(y[dimension])
+        );
+
+        var (gaps, furthestEnd) = (0, rectangles[0][dimension + 2]);
+        for (var i = 1; i < rectangles.Length; ++i) {
+            var r = rectangles[i];
+
+            if (furthestEnd <= r[dimension]) {
+                ++gaps;
+            }
+
+            furthestEnd = Math.Max(furthestEnd, r[dimension + 2]);
+        }
+
+        return gaps >= 2;
+    }
+
+    public bool CheckValidCuts(int n, int[][] rectangles)
+        => CheckCuts(rectangles, X) || CheckCuts(rectangles, Y);
+}