feat: add solutions to lc problem: No.2929 (#4452)

No.2929. Distribute Candies Among Children II

Author: yanglbme

solution/2900-2999/2929.Distribute Candies Among Children II/README.md

@@ -172,6 +172,30 @@ function distributeCandies(n: number, limit: number): number {
 }
 ```
 
+#### Rust
+
+```rust
+impl Solution {
+    pub fn distribute_candies(n: i32, limit: i32) -> i64 {
+        if n > 3 * limit {
+            return 0;
+        }
+        let mut ans = Self::comb2(n + 2);
+        if n > limit {
+            ans -= 3 * Self::comb2(n - limit + 1);
+        }
+        if n - 2 >= 2 * limit {
+            ans += 3 * Self::comb2(n - 2 * limit);
+        }
+        ans
+    }
+
+    fn comb2(n: i32) -> i64 {
+        (n as i64) * (n as i64 - 1) / 2
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

solution/2900-2999/2929.Distribute Candies Among Children II/README_EN.md

@@ -170,6 +170,30 @@ function distributeCandies(n: number, limit: number): number {
 }
 ```
 
+#### Rust
+
+```rust
+impl Solution {
+    pub fn distribute_candies(n: i32, limit: i32) -> i64 {
+        if n > 3 * limit {
+            return 0;
+        }
+        let mut ans = Self::comb2(n + 2);
+        if n > limit {
+            ans -= 3 * Self::comb2(n - limit + 1);
+        }
+        if n - 2 >= 2 * limit {
+            ans += 3 * Self::comb2(n - 2 * limit);
+        }
+        ans
+    }
+
+    fn comb2(n: i32) -> i64 {
+        (n as i64) * (n as i64 - 1) / 2
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

solution/2900-2999/2929.Distribute Candies Among Children II/Solution.rs

@@ -0,0 +1,19 @@
+impl Solution {
+    pub fn distribute_candies(n: i32, limit: i32) -> i64 {
+        if n > 3 * limit {
+            return 0;
+        }
+        let mut ans = Self::comb2(n + 2);
+        if n > limit {
+            ans -= 3 * Self::comb2(n - limit + 1);
+        }
+        if n - 2 >= 2 * limit {
+            ans += 3 * Self::comb2(n - 2 * limit);
+        }
+        ans
+    }
+
+    fn comb2(n: i32) -> i64 {
+        (n as i64) * (n as i64 - 1) / 2
+    }
+}