rs: add «2962. Count Subarrays Where Max Element Appears at Least K Times»

Signed-off-by: Matej Focko <me@mfocko.xyz>

rs/count-subarrays-where-max-element-appears-at-least-k-times.rs

@@ -0,0 +1,25 @@
+impl Solution {
+    pub fn count_subarrays(nums: Vec<i32>, mut k: i32) -> i64 {
+        let m = *nums.iter().max().expect("1 ≤ nums.len() ≤ 10⁵");
+        let mut counter: i64 = 0;
+
+        let mut i: usize = 0;
+        for j in 0..nums.len() {
+            if nums[j] == m {
+                k -= 1;
+            }
+
+            while k == 0 {
+                if nums[i] == m {
+                    k += 1;
+                }
+
+                i += 1;
+            }
+
+            counter += i as i64;
+        }
+
+        counter
+    }
+}