s0090

include/s0090_subsets_ii.hpp

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+#ifndef S0090_SUBSETS_II_HPP
+#define S0090_SUBSETS_II_HPP
+
+#include <algorithm>
+#include <vector>
+
+using namespace std;
+
+class S0090 {
+ public:
+  vector<vector<int>> subsetsWithDup(vector<int>& nums);
+};
+
+#endif

src/s0090_subsets_ii.cpp

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+#include "s0090_subsets_ii.hpp"
+
+void subsetsWithDupDFS(vector<int> &subset, vector<vector<int>> &result,
+                       vector<int> &nums, int startIndex, vector<bool> &used) {
+  int size = nums.size();
+  // 结束条件
+  if (startIndex == size) return;
+
+  for (int i = startIndex; i < size; ++i) {
+    // 剪枝，保留树枝重复
+    if (i > 0 && nums[i] == nums[i - 1] && used[i - 1] == false) continue;
+    subset.push_back(nums[i]);
+    result.push_back(subset);
+    used[i] = true;
+    subsetsWithDupDFS(subset, result, nums, i + 1, used);
+    used[i] = false;
+    subset.pop_back();
+  }
+}
+
+vector<vector<int>> S0090::subsetsWithDup(vector<int> &nums) {
+  vector<int> subset{};
+  vector<vector<int>> result{};
+  vector<bool> used(nums.size(), false);
+  sort(nums.begin(), nums.end());
+  subsetsWithDupDFS(subset, result, nums, 0, used);
+  result.push_back(vector<int>{});
+  return result;
+}