feat: add contains duplicate problem solution

Author: bujosa

src/easy/contains_duplicate.rs

@@ -0,0 +1,38 @@
+#![allow(dead_code)]
+pub fn contains_duplicate(nums: Vec<i32>) -> bool {
+    use std::collections::HashSet;
+    let mut set = HashSet::new();
+    for num in nums {
+        if set.contains(&num) {
+            return true;
+        }
+        set.insert(num);
+    }
+    false
+}
+
+/*
+   Algorithm - Hash Set
+   - Create a hash set
+   - Iterate through the vector
+       - If the hash set contains the current number
+           - Return true
+       - Else
+           - Insert the current number into the hash set
+   - Return false
+
+   Time Complexity = O(n)
+   Space Complexity = O(n)
+*/
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_contains_duplicate() {
+        assert_eq!(contains_duplicate(vec![1, 2, 3, 1]), true);
+        assert_eq!(contains_duplicate(vec![1, 2, 3, 4]), false);
+        assert_eq!(contains_duplicate(vec![1, 1, 1, 3, 3, 4, 3, 2, 4, 2]), true);
+    }
+}

src/easy/mod.rs

@@ -2,6 +2,7 @@ pub mod add_binary;
 pub mod balanced_binary_tree;
 pub mod binary_tree_inorder_traversal;
 pub mod climbing_stairs;
+pub mod contains_duplicate;
 pub mod convert_sorted_array_to_binary_search_tree;
 pub mod implement_strstr;
 pub mod length_of_last_word;
@@ -24,4 +25,4 @@ pub mod search_insert_position;
 pub mod sqrt_x;
 pub mod symmetric_tree;
 pub mod two_sum;
-pub mod valid_parentheses;
+pub mod valid_parentheses;

src/readme.md

@@ -30,6 +30,7 @@
   - [x] [112. Path sum](src/easy/path_sum.rs)
   - [x] [118. Pascal's triangle](src/easy/pascals_triangle.rs)
   - [x] [119. Pascal's triangle II](src/easy/pascals_triangle.rs)
+  - [x] [217. Contains duplicate](src/easy/contains_duplicate.rs)
   - [x] [234. Palindrome linked list](src/easy/palindrome_linked_list.rs)
 - [ ] [Medium](src/medium)
   - [x] [2. Add two numbers](src/medium/add_two_numbers.rs)

theory/categories/1.arrays_&_hashing/readme.md

@@ -65,9 +65,9 @@
 
 ## Problems
 
-- [ ] [1. Contains Duplicate](https://leetcode.com/problems/contains-duplicate/) | Easy problem | [Solution](src/easy/contains_duplicate.rs)
+- [x] [1. Contains Duplicate](https://leetcode.com/problems/contains-duplicate/) | Easy problem | [Solution](src/easy/contains_duplicate.rs)
 - [ ] [2. Valid Anagram](https://leetcode.com/problems/valid-anagram/) | Easy problem
-- [x] [3. Two Sum](https://leetcode.com/problems/two-sum/) [Solution](src/easy/two_sum.rs) | Easy problem
+- [x] [3. Two Sum](https://leetcode.com/problems/two-sum/) | Easy problem | [Solution](src/easy/two_sum.rs)
 - [ ] [4. Group Anagrams](https://leetcode.com/problems/group-anagrams/) | Medium Problem
 - [ ] [5. Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/) | Medium Problem
 - [ ] [6. Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/) | Medium Problem