java: add “1758. Minimum Changes To Make Alternating Binary String”

Signed-off-by: Matej Focko <me@mfocko.xyz>

java/minimum-changes-to-make-alternating-binary-string.java

@@ -0,0 +1,21 @@
+class Solution {
+    public int minOperations(String s) {
+        int startingZero = 0;
+        int startingOne = 0;
+
+        for (int i = 0; i < s.length(); ++i) {
+            char c = s.charAt(i);
+
+            if (c != '0' + i % 2) {
+                ++startingZero;
+            }
+
+            if (c != '0' + (i + 1) % 2) {
+                ++startingOne;
+            }
+        }
+
+        return Math.min(startingZero, startingOne);
+    }
+}
+