Added rust

src/main/rust/g0001_0100/s0001_two_sum/Solution.rs

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+// #Easy #Top_100_Liked_Questions #Top_Interview_Questions #Array #Hash_Table
+// #Data_Structure_I_Day_2_Array #Level_1_Day_13_Hashmap #Udemy_Arrays #Big_O_Time_O(n)_Space_O(n)
+// #2024_08_24_Time_0_ms_(100.00%)_Space_2.4_MB_(23.16%)
+
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn two_sum(numbers: Vec<i32>, target: i32) -> Vec<i32> {
+        let mut index_map: HashMap<i32, usize> = HashMap::new();
+
+        for (i, &num) in numbers.iter().enumerate() {
+            let required_num = target - num;
+            if let Some(&index) = index_map.get(&required_num) {
+                return vec![index as i32, i as i32];
+            }
+            index_map.insert(num, i);
+        }
+
+        vec![-1, -1]
+    }
+}

src/main/rust/g0001_0100/s0001_two_sum/readme.md

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+1\. Two Sum
+
+Easy
+
+Given an array of integers `nums` and an integer `target`, return _indices of the two numbers such that they add up to `target`_.
+
+You may assume that each input would have **_exactly_ one solution**, and you may not use the _same_ element twice.
+
+You can return the answer in any order.
+
+**Example 1:**
+
+**Input:** nums = [2,7,11,15], target = 9
+
+**Output:** [0,1]
+
+**Output:** Because nums[0] + nums[1] == 9, we return [0, 1]. 
+
+**Example 2:**
+
+**Input:** nums = [3,2,4], target = 6
+
+**Output:** [1,2] 
+
+**Example 3:**
+
+**Input:** nums = [3,3], target = 6
+
+**Output:** [0,1] 
+
+**Constraints:**
+
+*   <code>2 <= nums.length <= 10<sup>4</sup></code>
+*   <code>-10<sup>9</sup> <= nums[i] <= 10<sup>9</sup></code>
+*   <code>-10<sup>9</sup> <= target <= 10<sup>9</sup></code>
+*   **Only one valid answer exists.**
+
+**Follow-up:** Can you come up with an algorithm that is less than <code>O(n<sup>2</sup>) </code>time complexity?

src/main/rust/g0001_0100/s0002_add_two_numbers/Solution.rs

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+// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Math #Linked_List #Recursion
+// #Data_Structure_II_Day_10_Linked_List #Programming_Skills_II_Day_15
+// #Big_O_Time_O(max(N,M))_Space_O(max(N,M)) #2024_08_24_Time_0_ms_(100.00%)_Space_2.2_MB_(14.25%)
+
+// Definition for singly-linked list.
+// #[derive(PartialEq, Eq, Clone, Debug)]
+// pub struct ListNode {
+//   pub val: i32,
+//   pub next: Option<Box<ListNode>>
+// }
+// 
+// impl ListNode {
+//   #[inline]
+//   fn new(val: i32) -> Self {
+//     ListNode {
+//       next: None,
+//       val
+//     }
+//   }
+// }
+impl Solution {
+    pub fn add_two_numbers(
+        l1: Option<Box<ListNode>>, 
+        l2: Option<Box<ListNode>>
+    ) -> Option<Box<ListNode>> {
+        let mut p = l1;
+        let mut q = l2;
+        let mut dummy_head = Box::new(ListNode::new(0));
+        let mut curr = &mut dummy_head;
+        let mut carry = 0;
+
+        while p.is_some() || q.is_some() {
+            let x = p.as_ref().map_or(0, |node| node.val);
+            let y = q.as_ref().map_or(0, |node| node.val);
+            let sum = carry + x + y;
+            carry = sum / 10;
+            curr.next = Some(Box::new(ListNode::new(sum % 10)));
+            curr = curr.next.as_mut().unwrap();
+
+            if let Some(node) = p {
+                p = node.next;
+            }
+            if let Some(node) = q {
+                q = node.next;
+            }
+        }
+
+        if carry > 0 {
+            curr.next = Some(Box::new(ListNode::new(carry)));
+        }
+
+        dummy_head.next
+    }
+}

src/main/rust/g0001_0100/s0002_add_two_numbers/readme.md

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+2\. Add Two Numbers
+
+Medium
+
+You are given two **non-empty** linked lists representing two non-negative integers. The digits are stored in **reverse order**, and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.
+
+You may assume the two numbers do not contain any leading zero, except the number 0 itself.
+
+**Example 1:**
+
+![](https://assets.leetcode.com/uploads/2020/10/02/addtwonumber1.jpg)
+
+**Input:** l1 = [2,4,3], l2 = [5,6,4]
+
+**Output:** [7,0,8]
+
+**Explanation:** 342 + 465 = 807. 
+
+**Example 2:**
+
+**Input:** l1 = [0], l2 = [0]
+
+**Output:** [0] 
+
+**Example 3:**
+
+**Input:** l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
+
+**Output:** [8,9,9,9,0,0,0,1] 
+
+**Constraints:**
+
+*   The number of nodes in each linked list is in the range `[1, 100]`.
+*   `0 <= Node.val <= 9`
+*   It is guaranteed that the list represents a number that does not have leading zeros.

src/main/rust/g0001_0100/s0003_longest_substring_without_repeating_characters/Solution.rs

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+// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #String #Hash_Table #Sliding_Window
+// #Algorithm_I_Day_6_Sliding_Window #Level_2_Day_14_Sliding_Window/Two_Pointer #Udemy_Strings
+// #Big_O_Time_O(n)_Space_O(1) #2024_08_24_Time_0_ms_(100.00%)_Space_2.3_MB_(28.72%)
+
+impl Solution {
+    pub fn length_of_longest_substring(s: String) -> i32 {
+        // Array to store last seen indices of characters
+        let mut last_indices = [-1; 256];
+        let mut max_len = 0;
+        let mut cur_len = 0;
+        let mut start = 0;
+
+        // Convert string to bytes to use indexing
+        let bytes = s.as_bytes();
+        for (i, &cur) in bytes.iter().enumerate() {
+            // Cast byte to usize to use as an index
+            let cur = cur as usize;
+
+            if last_indices[cur] < start as i32 {
+                last_indices[cur] = i as i32;
+                cur_len += 1;
+            } else {
+                let last_index = last_indices[cur];
+                start = (last_index + 1) as usize;
+                cur_len = i - start + 1;
+                last_indices[cur] = i as i32;
+            }
+
+            if cur_len > max_len {
+                max_len = cur_len;
+            }
+        }
+
+        max_len as i32
+    }
+}

src/main/rust/g0001_0100/s0003_longest_substring_without_repeating_characters/readme.md

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+3\. Longest Substring Without Repeating Characters
+
+Medium
+
+Given a string `s`, find the length of the **longest substring** without repeating characters.
+
+**Example 1:**
+
+**Input:** s = "abcabcbb"
+
+**Output:** 3
+
+**Explanation:** The answer is "abc", with the length of 3. 
+
+**Example 2:**
+
+**Input:** s = "bbbbb"
+
+**Output:** 1
+
+**Explanation:** The answer is "b", with the length of 1. 
+
+**Example 3:**
+
+**Input:** s = "pwwkew"
+
+**Output:** 3
+
+**Explanation:** The answer is "wke", with the length of 3. Notice that the answer must be a substring, "pwke" is a subsequence and not a substring. 
+
+**Example 4:**
+
+**Input:** s = ""
+
+**Output:** 0 
+
+**Constraints:**
+
+*   <code>0 <= s.length <= 5 * 10<sup>4</sup></code>
+*   `s` consists of English letters, digits, symbols and spaces.

src/main/rust/g0001_0100/s0004_median_of_two_sorted_arrays/Solution.rs

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+// #Hard #Top_100_Liked_Questions #Top_Interview_Questions #Array #Binary_Search #Divide_and_Conquer
+// #Big_O_Time_O(log(min(N,M)))_Space_O(1) #2024_08_24_Time_0_ms_(100.00%)_Space_2.2_MB_(39.80%)
+
+impl Solution {
+    pub fn find_median_sorted_arrays(nums1: Vec<i32>, nums2: Vec<i32>) -> f64 {
+        let (nums1, nums2) = if nums1.len() > nums2.len() {
+            // Ensures nums1 is the smaller array
+            (nums2, nums1)
+        } else {
+            (nums1, nums2)
+        };
+
+        let n1 = nums1.len();
+        let n2 = nums2.len();
+        let mut low = 0;
+        let mut high = n1;
+
+        while low <= high {
+            let cut1 = (low + high) / 2;
+            let cut2 = (n1 + n2 + 1) / 2 - cut1;
+
+            let l1 = if cut1 == 0 { i32::MIN } else { nums1[cut1 - 1] };
+            let l2 = if cut2 == 0 { i32::MIN } else { nums2[cut2 - 1] };
+            let r1 = if cut1 == n1 { i32::MAX } else { nums1[cut1] };
+            let r2 = if cut2 == n2 { i32::MAX } else { nums2[cut2] };
+
+            if l1 <= r2 && l2 <= r1 {
+                // Found the correct partition
+                if (n1 + n2) % 2 == 0 {
+                    return (f64::from(l1.max(l2)) + f64::from(r1.min(r2))) / 2.0;
+                } else {
+                    return f64::from(l1.max(l2));
+                }
+            } else if l1 > r2 {
+                high = cut1 - 1;
+            } else {
+                low = cut1 + 1;
+            }
+        }
+
+        // Fallback case, should never hit
+        0.0
+    }
+}

src/main/rust/g0001_0100/s0004_median_of_two_sorted_arrays/readme.md

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+4\. Median of Two Sorted Arrays
+
+Hard
+
+Given two sorted arrays `nums1` and `nums2` of size `m` and `n` respectively, return **the median** of the two sorted arrays.
+
+The overall run time complexity should be `O(log (m+n))`.
+
+**Example 1:**
+
+**Input:** nums1 = [1,3], nums2 = [2]
+
+**Output:** 2.00000
+
+**Explanation:** merged array = [1,2,3] and median is 2. 
+
+**Example 2:**
+
+**Input:** nums1 = [1,2], nums2 = [3,4]
+
+**Output:** 2.50000
+
+**Explanation:** merged array = [1,2,3,4] and median is (2 + 3) / 2 = 2.5. 
+
+**Example 3:**
+
+**Input:** nums1 = [0,0], nums2 = [0,0]
+
+**Output:** 0.00000 
+
+**Example 4:**
+
+**Input:** nums1 = [], nums2 = [1]
+
+**Output:** 1.00000 
+
+**Example 5:**
+
+**Input:** nums1 = [2], nums2 = []
+
+**Output:** 2.00000 
+
+**Constraints:**
+
+*   `nums1.length == m`
+*   `nums2.length == n`
+*   `0 <= m <= 1000`
+*   `0 <= n <= 1000`
+*   `1 <= m + n <= 2000`
+*   <code>-10<sup>6</sup> <= nums1[i], nums2[i] <= 10<sup>6</sup></code>

src/main/rust/g0001_0100/s0005_longest_palindromic_substring/Solution.rs

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+// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #String #Dynamic_Programming
+// #Data_Structure_II_Day_9_String #Algorithm_II_Day_14_Dynamic_Programming
+// #Dynamic_Programming_I_Day_17 #Udemy_Strings #Big_O_Time_O(n)_Space_O(n)
+// #2024_08_24_Time_1_ms_(92.60%)_Space_2.2_MB_(20.49%)
+
+impl Solution {
+    pub fn longest_palindrome(s: String) -> String {
+        let n = s.len();
+        if n == 0 {
+            return String::new();
+        }
+
+        // Step 1: Transform the string to avoid even/odd length issues
+        let mut new_str = Vec::with_capacity(n * 2 + 1);
+        new_str.push('#');
+        for c in s.chars() {
+            new_str.push(c);
+            new_str.push('#');
+        }
+
+        let m = new_str.len();
+        let mut dp = vec![0; m];
+        let mut friend_center = 0;
+        let mut friend_radius = 0;
+        let mut lps_center = 0;
+        let mut lps_radius = 0;
+
+        // Step 2: Apply Manacher's Algorithm
+        for i in 0..m {
+            dp[i] = if friend_center + friend_radius > i {
+                dp[2 * friend_center - i].min(friend_center + friend_radius - i)
+            } else {
+                1
+            };
+
+            while i + dp[i] < m && i >= dp[i] && new_str[i + dp[i]] == new_str[i - dp[i]] {
+                dp[i] += 1;
+            }
+
+            if friend_center + friend_radius < i + dp[i] {
+                friend_center = i;
+                friend_radius = dp[i];
+            }
+
+            if lps_radius < dp[i] {
+                lps_center = i;
+                lps_radius = dp[i];
+            }
+        }
+
+        // Step 3: Extract the longest palindromic substring
+        let start = (lps_center - lps_radius + 1) / 2;
+        let end = (lps_center + lps_radius - 1) / 2;
+        s[start..end].to_string()
+    }
+}