1

Author: Ainevsia

notes/src/day1/lc27.md

@@ -65,4 +65,37 @@ impl Solution {
         a as i32
     }
 }
+```
+
+std强大的标准库 Vec上retain方法
+
+```rust
+
+impl Solution {
+    pub fn remove_element(nums: &mut Vec<i32>, val: i32) -> i32 {
+        nums.retain(|&x| x != val);
+        nums.len() as i32
+    }
+}
+
+```
+
+slow指针用来存储需要留下元素应该存放的地址，fast指针是当前处理的元素
+
+```rust
+impl Solution {
+    pub fn remove_element(nums: &mut Vec<i32>, val: i32) -> i32 {
+        let mut slow: usize = 0usize;    // the result elem
+        let mut fast: usize = 0usize;    // the processing elem
+        while fast < nums.len() {
+            if nums[fast] == val { fast += 1usize }
+            else {
+                nums[slow] = nums[fast]; // move elem
+                slow += 1usize;
+                fast += 1usize;
+            }
+        }
+        slow as i32
+    }
+}
 ```