Update 0090.子集II.md

Author: fwqaaq

problems/0090.子集II.md

@@ -440,7 +440,7 @@ impl Solution {
         let len = nums.len();
         // if start_index >= len { return; }
         for i in start_index..len {
-            if i > 0 && nums[i] == nums[i - 1] && used[i - 1] == false { continue; }
+            if i > 0 && nums[i] == nums[i - 1] && !used[i - 1] { continue; }
             path.push(nums[i]);
             used[i] = true;
             Self::backtracking(result, path, nums, i + 1, used);
@@ -449,18 +449,46 @@ impl Solution {
         }
     }
 
-    pub fn subsets_with_dup(nums: Vec<i32>) -> Vec<Vec<i32>> {
+    pub fn subsets_with_dup(mut nums: Vec<i32>) -> Vec<Vec<i32>> {
         let mut result: Vec<Vec<i32>> = Vec::new();
         let mut path: Vec<i32> = Vec::new();
         let mut used = vec![false; nums.len()];
-        let mut nums = nums;
         nums.sort();
         Self::backtracking(&mut result, &mut path, &nums, 0, &mut used);
         result
     }
 }
 ```
 
+set 去重版本
+
+```rust
+use std::collections::HashSet;
+impl Solution {
+    pub fn subsets_with_dup(mut nums: Vec<i32>) -> Vec<Vec<i32>> {
+        let mut res = HashSet::new();
+        let mut path = vec![];
+        nums.sort();
+        Self::backtracking(&nums, &mut path, &mut res, 0);
+        res.into_iter().collect()
+    }
+
+    pub fn backtracking(
+        nums: &Vec<i32>,
+        path: &mut Vec<i32>,
+        res: &mut HashSet<Vec<i32>>,
+        start_index: usize,
+    ) {
+        res.insert(path.clone());
+        for i in start_index..nums.len() {
+            path.push(nums[i]);
+            Self::backtracking(nums, path, res, i + 1);
+            path.pop();
+        }
+    }
+}
+```
+
 ### C 
 
 ```c