20241024 finished.

src/problem/p2552_count_increasing_quadruplets.rs

@@ -3,32 +3,31 @@
  */
 pub struct Solution {}
 
-
 // submission codes start here
 
 impl Solution {
     pub fn count_quadruplets(nums: Vec<i32>) -> i64 {
         let nums: Vec<usize> = nums.iter().map(|x| *x as usize).collect();
         let n = nums.len();
-        let mut pre = vec![0;n + 1];
+        let mut pre = vec![0; n + 1];
         let mut result = 0;
-        
+
         for j in 0..n {
             let mut suffix = 0;
-            
+
             for k in (j + 1..n).rev() {
                 if nums[j] > nums[k] {
                     result += pre[nums[k]] * suffix;
-                } else { 
+                } else {
                     suffix += 1;
                 }
             }
-            
+
             for i in nums[j] + 1..=n {
                 pre[i] += 1;
             }
         }
-        
+
         result
     }
 }
@@ -41,6 +40,6 @@ mod tests {
 
     #[test]
     fn test_2552() {
-        assert_eq!(2, Solution::count_quadruplets(vec![1,3,2,4,5]));
+        assert_eq!(2, Solution::count_quadruplets(vec![1, 3, 2, 4, 5]));
     }
 }