java: add «2134. Minimum Swaps to Group All 1's Together II»

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

java/minimum-swaps-to-group-all-1s-together-ii.java

@@ -0,0 +1,27 @@
+class Solution {
+  private int countOnes(int[] nums, int upperBound) {
+    var count = 0;
+
+    for (int i = 0; i < upperBound; ++i) {
+      if (nums[i] == 1) {
+        ++count;
+      }
+    }
+
+    return count;
+  }
+
+  public int minSwaps(int[] nums) {
+    var ones = countOnes(nums, nums.length);
+    var inWindow = countOnes(nums, ones);
+
+    var minSwaps = nums.length;
+    for (int i = 0; i < nums.length; ++i) {
+      inWindow += nums[(i + ones) % nums.length] - nums[i];
+
+      minSwaps = Math.min(minSwaps, ones - inWindow);
+    }
+
+    return minSwaps;
+  }
+}