cs: add “62. Unique Paths”

Signed-off-by: Matej Focko <mfocko@redhat.com>

cs/unique-paths.cs

@@ -0,0 +1,25 @@
+public class Solution {
+    private static int Right(List<int> row, int size, int idx) {
+        if (idx >= size) {
+            return 0;
+        }
+
+        return row[idx];
+    }
+
+    public int UniquePaths(int m, int n) {
+        var bottom = new List<int>(Enumerable.Repeat(1, n));
+
+        for (var y = m - 2; y >= 0; --y) {
+            var above = new List<int>(Enumerable.Repeat(0, n));
+
+            for (var x = n - 1; x >= 0; --x) {
+                above[x] = Right(above, n, x + 1) + bottom[x];
+            }
+
+            bottom = above;
+        }
+
+        return bottom[0];
+    }
+}