diff --git a/1323_maximum_69_number/src/main.rs b/1323_maximum_69_number/src/lib.rs
similarity index 93%
rename from 1323_maximum_69_number/src/main.rs
rename to 1323_maximum_69_number/src/lib.rs
index 713e374..a921d57 100644
--- a/1323_maximum_69_number/src/main.rs
+++ b/1323_maximum_69_number/src/lib.rs
@@ -1,6 +1,4 @@
-fn main() {}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn maximum69_number(num: i32) -> i32 {
diff --git a/191_number_of_1_bits/src/main.rs b/191_number_of_1_bits/src/lib.rs
similarity index 75%
rename from 191_number_of_1_bits/src/main.rs
rename to 191_number_of_1_bits/src/lib.rs
index 46d381c..7aa61a0 100644
--- a/191_number_of_1_bits/src/main.rs
+++ b/191_number_of_1_bits/src/lib.rs
@@ -1,8 +1,4 @@
-fn main() {
-    println!("Hello, world!");
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn hamming_weight(mut n: i32) -> i32 {
diff --git a/1920_build_array_from_permutation/src/main.rs b/1920_build_array_from_permutation/src/lib.rs
similarity index 68%
rename from 1920_build_array_from_permutation/src/main.rs
rename to 1920_build_array_from_permutation/src/lib.rs
index 058015d..5431008 100644
--- a/1920_build_array_from_permutation/src/main.rs
+++ b/1920_build_array_from_permutation/src/lib.rs
@@ -1,8 +1,4 @@
-fn main() {
-    println!("Hello, world!");
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn build_array(nums: Vec<i32>) -> Vec<i32> {
diff --git a/202_happy_number/src/main.rs b/202_happy_number/src/lib.rs
similarity index 89%
rename from 202_happy_number/src/main.rs
rename to 202_happy_number/src/lib.rs
index 45c50a4..1e01d5b 100644
--- a/202_happy_number/src/main.rs
+++ b/202_happy_number/src/lib.rs
@@ -1,10 +1,6 @@
 use std::collections::HashSet;
 
-fn main() {
-    println!("Hello, world!");
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn is_happy(mut n: i32) -> bool {
diff --git a/206_reverse_linked_list/src/main.rs b/206_reverse_linked_list/src/lib.rs
similarity index 94%
rename from 206_reverse_linked_list/src/main.rs
rename to 206_reverse_linked_list/src/lib.rs
index 081ffed..8975ac5 100644
--- a/206_reverse_linked_list/src/main.rs
+++ b/206_reverse_linked_list/src/lib.rs
@@ -1,9 +1,3 @@
-use std::ops::Deref;
-
-fn main() {
-    println!("Hello, world!");
-}
-
 #[derive(PartialEq, Eq, Clone, Debug)]
 pub struct ListNode {
     pub val: i32,
@@ -17,7 +11,7 @@ impl ListNode {
     }
 }
 
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn reverse_list(head: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
diff --git a/2807_insert_greatest_common_divisors_in_linked_list/src/main.rs b/2807_insert_greatest_common_divisors_in_linked_list/src/lib.rs
similarity index 85%
rename from 2807_insert_greatest_common_divisors_in_linked_list/src/main.rs
rename to 2807_insert_greatest_common_divisors_in_linked_list/src/lib.rs
index 65121a1..ec60624 100644
--- a/2807_insert_greatest_common_divisors_in_linked_list/src/main.rs
+++ b/2807_insert_greatest_common_divisors_in_linked_list/src/lib.rs
@@ -1,8 +1,4 @@
-fn main() {
-    println!("{}", Solution::gcd(10, 25));
-}
-
-struct Solution;
+pub struct Solution;
 
 #[derive(PartialEq, Eq, Clone, Debug)]
 pub struct ListNode {
@@ -10,13 +6,6 @@ pub struct ListNode {
     pub next: Option<Box<ListNode>>,
 }
 
-impl ListNode {
-    #[inline]
-    fn new(val: i32) -> Self {
-        ListNode { next: None, val }
-    }
-}
-
 impl Solution {
     pub fn insert_greatest_common_divisors(
         mut head: Option<Box<ListNode>>,
diff --git a/2894_divisible_and_non_divisible_sums_difference/src/main.rs b/2894_divisible_and_non_divisible_sums_difference/src/lib.rs
similarity index 81%
rename from 2894_divisible_and_non_divisible_sums_difference/src/main.rs
rename to 2894_divisible_and_non_divisible_sums_difference/src/lib.rs
index 1c1b8fb..73e2467 100644
--- a/2894_divisible_and_non_divisible_sums_difference/src/main.rs
+++ b/2894_divisible_and_non_divisible_sums_difference/src/lib.rs
@@ -1,8 +1,4 @@
-fn main() {
-    println!("Hello, world!");
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn difference_of_sums(n: i32, m: i32) -> i32 {
diff --git a/3110_score_of_a_string/src/main.rs b/3110_score_of_a_string/src/lib.rs
similarity index 66%
rename from 3110_score_of_a_string/src/main.rs
rename to 3110_score_of_a_string/src/lib.rs
index 4eb9a5b..a664165 100644
--- a/3110_score_of_a_string/src/main.rs
+++ b/3110_score_of_a_string/src/lib.rs
@@ -1,8 +1,4 @@
-fn main() {
-    println!("{}", Solution::score_of_string("hello".to_string()));
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn score_of_string(s: String) -> i32 {
diff --git a/342_power_of_four/src/main.rs b/342_power_of_four/src/lib.rs
similarity index 84%
rename from 342_power_of_four/src/main.rs
rename to 342_power_of_four/src/lib.rs
index 85dcc94..5a8c626 100644
--- a/342_power_of_four/src/main.rs
+++ b/342_power_of_four/src/lib.rs
@@ -1,8 +1,4 @@
-fn main() {
-    println!("Hello, world!");
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn is_power_of_four(mut n: i32) -> bool {
diff --git a/43_multiply_strings/src/main.rs b/43_multiply_strings/src/lib.rs
similarity index 94%
rename from 43_multiply_strings/src/main.rs
rename to 43_multiply_strings/src/lib.rs
index 21fc508..9710865 100644
--- a/43_multiply_strings/src/main.rs
+++ b/43_multiply_strings/src/lib.rs
@@ -1,12 +1,6 @@
 use std::cmp;
 
-fn main() {
-    let x = "000".to_string();
-    let y = "0".to_string();
-    println!("{}", Solution::plus(x, y));
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn multiply(x: String, y: String) -> String {
diff --git a/62_unique_path/src/main.rs b/62_unique_path/src/lib.rs
similarity index 81%
rename from 62_unique_path/src/main.rs
rename to 62_unique_path/src/lib.rs
index f29d441..0284b9a 100644
--- a/62_unique_path/src/main.rs
+++ b/62_unique_path/src/lib.rs
@@ -1,8 +1,4 @@
-fn main() {
-    println!("Hello, world!");
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn unique_paths(m: i32, n: i32) -> i32 {
diff --git a/63_unique_path_2/src/main.rs b/63_unique_path_2/src/lib.rs
similarity index 82%
rename from 63_unique_path_2/src/main.rs
rename to 63_unique_path_2/src/lib.rs
index 92f8d36..ec70180 100644
--- a/63_unique_path_2/src/main.rs
+++ b/63_unique_path_2/src/lib.rs
@@ -1,11 +1,4 @@
-fn main() {
-    println!(
-        "{}",
-        Solution::unique_paths_with_obstacles(vec![vec![0], vec![1]])
-    );
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn unique_paths_with_obstacles(obstacle_grid: Vec<Vec<i32>>) -> i32 {
diff --git a/64_minimum_path_sum/src/main.rs b/64_minimum_path_sum/src/lib.rs
similarity index 89%
rename from 64_minimum_path_sum/src/main.rs
rename to 64_minimum_path_sum/src/lib.rs
index 56deb42..1fb8507 100644
--- a/64_minimum_path_sum/src/main.rs
+++ b/64_minimum_path_sum/src/lib.rs
@@ -1,8 +1,4 @@
-fn main() {
-    println!("Hello, world!");
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn min_path_sum(mut grid: Vec<Vec<i32>>) -> i32 {
diff --git a/679_24_game/src/main.rs b/679_24_game/src/lib.rs
similarity index 90%
rename from 679_24_game/src/main.rs
rename to 679_24_game/src/lib.rs
index 2336fd6..6a027dc 100644
--- a/679_24_game/src/main.rs
+++ b/679_24_game/src/lib.rs
@@ -1,16 +1,10 @@
-fn main() {
-    println!("{}", Solution::judge_point24(vec![1, 5, 9, 1]));
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn judge_point24(cards: Vec<i32>) -> bool {
         let mut stack: Vec<Vec<f64>> = vec![cards.iter().map(|&v| v as f64).collect()];
 
         while let Some(cards) = stack.pop() {
-            println!("{:?}", cards);
-
             if cards.len() == 1 {
                 if (cards.first().unwrap() - 24f64).abs() < 1e-6 {
                     return true;
@@ -27,7 +21,6 @@ impl Solution {
                     let mut left_cards = cards.clone();
                     left_cards.remove(j);
                     left_cards.remove(i);
-                    println!("{i} {j} {:?}", left_cards);
 
                     let mut new_cards = left_cards.clone();
                     new_cards.push(a + b);
diff --git a/837_new_21_game/src/main.rs b/837_new_21_game/src/lib.rs
similarity index 91%
rename from 837_new_21_game/src/main.rs
rename to 837_new_21_game/src/lib.rs
index 3380584..e559705 100644
--- a/837_new_21_game/src/main.rs
+++ b/837_new_21_game/src/lib.rs
@@ -1,8 +1,4 @@
-fn main() {
-    println!("Hello, world!");
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn new21_game(n: i32, k: i32, max_pts: i32) -> f64 {
diff --git a/980_unique_path_3/src/main.rs b/980_unique_path_3/src/lib.rs
similarity index 94%
rename from 980_unique_path_3/src/main.rs
rename to 980_unique_path_3/src/lib.rs
index c6b1db8..4c5c535 100644
--- a/980_unique_path_3/src/main.rs
+++ b/980_unique_path_3/src/lib.rs
@@ -1,11 +1,4 @@
-fn main() {
-    println!(
-        "{}",
-        Solution::unique_paths_iii(vec![vec![1, 0, 0, 0], vec![0, 0, 0, 0], vec![0, 0, 2, -1]])
-    );
-}
-
-struct Solution;
+pub struct Solution;
 
 impl Solution {
     pub fn unique_paths_iii(grid: Vec<Vec<i32>>) -> i32 {