some leetcode, we're back

leetcode_problemset/problemsets/subsets.cpp

@@ -0,0 +1,30 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+vector<vector<int>> getAllSubsets(vector<int> &arr, vector<int> &out, int i, int n) {
+
+    vector<vector<int>> ans;
+
+    if (i >= n) {
+        ans.emplace_back(out);
+        return ans;
+    }
+
+    // not pick
+    vector<vector<int>> not_pick = getAllSubsets(arr, out, i + 1, n);
+    ans.insert(ans.end(), not_pick.begin(), not_pick.end());
+
+    // pick
+    out.emplace_back(arr[i]);
+    vector<vector<int>> pick = getAllSubsets(arr, out, i + 1, n);
+    ans.insert(ans.end(), pick.begin(), pick.end());
+    out.pop_back();
+
+    return ans;
+}
+
+vector<vector<int>> subsets(vector<int>& nums) {   
+    vector<int> out;
+    vector<vector<int>> res = getAllSubsets(nums, out, 0, nums.size());
+    return res;
+}

leetcode_problemset/problemsets/sum_of_all_subset_xor.cpp

@@ -0,0 +1,30 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int getAllSubsets(vector<int> &arr, vector<int> &ans, int i, int n) {
+
+    if(i >= n) {
+        int xor_cal = 0;
+        for(int k = 0; k < (int)ans.size(); ++k) {
+            xor_cal ^= ans[k];
+        }
+        return xor_cal;
+    }
+
+    // not pick
+    int not_pick = getAllSubsets(arr,ans,i+1,n);
+
+    // pick
+    ans.emplace_back(arr[i]);
+    int pick = getAllSubsets(arr,ans,i+1,n);
+    ans.pop_back();
+
+    return not_pick + pick;
+}
+
+int subsetXORSum(vector<int> &nums){
+
+    vector<int> ans;
+    return getAllSubsets(nums,ans,0,nums.size());
+
+}