Merge pull request #1531 from cezarbbb/Backtracking04

添加 0090.子集II Rust版本

problems/0090.子集II.md

@@ -367,6 +367,36 @@ function subsetsWithDup(nums: number[]): number[][] {
 };
 ```
 
+### Rust
+
+```Rust
+impl Solution {
+    fn backtracking(result: &mut Vec<Vec<i32>>, path: &mut Vec<i32>, nums: &Vec<i32>, start_index: usize, used: &mut Vec<bool>) {
+        result.push(path.clone());
+        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; }
+            path.push(nums[i]);
+            used[i] = true;
+            Self::backtracking(result, path, nums, i + 1, used);
+            used[i] = false;
+            path.pop();
+        }
+    }
+
+    pub fn subsets_with_dup(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
+    }
+}
+```
+
 ### C 
 
 ```c