Permutations II

Author: valmsmith39a

src/Review_2024/PermutationsII.java

@@ -0,0 +1,35 @@
+package Review_2024;
+
+import java.util.List;
+import java.util.Arrays;
+import java.util.ArrayList;
+
+public class PermutationsII {
+
+	public List<List<Integer>> permuteUnique(int[] nums) {
+		List<List<Integer>> result = new ArrayList<>();
+		Arrays.sort(nums);
+		boolean[] used = new boolean[nums.length];
+		backtrack(nums, new ArrayList<>(), used, result);
+		return result;
+	}
+
+	private void backtrack(int[] nums, List<Integer> current, boolean[] used, List<List<Integer>> result) {
+		if (current.size() == nums.length) {
+			result.add(new ArrayList<>(current));
+			return;
+		}
+
+		for (int i = 0; i < nums.length; i++) {
+			if (used[i] || (i > 0 && nums[i] == nums[i - 1] && !used[i - 1])) {
+				continue;
+			}
+			current.add(nums[i]);
+			used[i] = true;
+			backtrack(nums, current, used, result);
+
+			current.remove(current.size() - 1);
+			used[i] = false;
+		}
+	}
+}