subsets

Author: zgpeace

code/LeetCode/src/backtracking/Subsets.java

@@ -0,0 +1,40 @@
+package backtracking;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+// https://leetcode.com/problems/subsets/
+public class Subsets {
+
+  public static void main(String[] args) {
+    int[] nums = new int[]{1,2,3};
+    Subsets obj = new Subsets();
+    List<List<Integer>> resultList = obj.subsets(nums);
+    System.out.println(Arrays.toString(resultList.toArray()));
+  }
+
+  public List<List<Integer>> subsets(int[] nums) {
+    List<List<Integer>> resultList = new ArrayList<List<Integer>>();
+    // dfs
+    dfs(nums, resultList, new ArrayList<Integer>(), 0);
+
+    return resultList;
+  }
+
+  private void dfs(int[] nums, List<List<Integer>> resultList, List<Integer> list, int index) {
+    // exit
+    if (nums == null || index == nums.length) {
+      resultList.add(new ArrayList<Integer>(list));
+      return;
+    }
+
+    // add item
+    list.add(nums[index]);
+    dfs(nums, resultList, list, index + 1);
+
+    // not add item
+    list.remove(list.size() - 1);
+    dfs(nums, resultList, list, index + 1);
+  }
+}