cs: add «1422. Maximum Score After Splitting a String»

URL:	https://leetcode.com/problems/maximum-score-after-splitting-a-string/
Signed-off-by: Matej Focko <me@mfocko.xyz>

cs/maximum-score-after-splitting-a-string.cs

@@ -0,0 +1,22 @@
+public class Solution {
+    public int MaxScore(string s) {
+        var ones = s.Skip(1).Count(c => c == '1');
+        var zeros = s.Take(1).Count(c => c == '0');
+
+        var foundScore = ones + zeros;
+        for (var i = 1; i < s.Length - 1; ++i) {
+            switch (s[i]) {
+                case '0':
+                    ++zeros;
+                    break;
+                case '1':
+                    --ones;
+                    break;
+            }
+
+            foundScore = Math.Max(foundScore, ones + zeros);
+        }
+
+        return foundScore;
+    }
+}