feature: solve 3_longest_substring_without_repeating_characters

Author: DawnDantes

src/solution/mod.rs

@@ -1,2 +1,3 @@
 mod s0001_two_sum;
 mod s0002_add_two_numbers;
+mod s0003_longest_substring_without_repeating_characters;

src/solution/s0003_longest_substring_without_repeating_characters.rs

@@ -0,0 +1,86 @@
+/**
+ * [3] Longest Substring Without Repeating Characters
+ *
+ * Given a string s, find the length of the longest <span data-keyword="substring-nonempty">substring</span> without repeating characters.
+ *  
+ * <strong class="example">Example 1:
+ *
+ * Input: s = "abcabcbb"
+ * Output: 3
+ * Explanation: The answer is "abc", with the length of 3.
+ *
+ * <strong class="example">Example 2:
+ *
+ * Input: s = "bbbbb"
+ * Output: 1
+ * Explanation: The answer is "b", with the length of 1.
+ *
+ * <strong class="example">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.
+ *
+ *  
+ * Constraints:
+ *
+ * 	0 <= s.length <= 5 * 10^4
+ * 	s consists of English letters, digits, symbols and spaces.
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/longest-substring-without-repeating-characters/
+// discuss: https://leetcode.com/problems/longest-substring-without-repeating-characters/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn length_of_longest_substring(s: String) -> i32 {
+        use std::{cmp::max, collections::HashMap};
+
+        let mut map = HashMap::<char, usize>::new();
+        let mut ans = 0;
+        let mut left: usize = 0;
+        let chars: Vec<char> = s.chars().collect();
+        for (index, ch) in chars.iter().enumerate() {
+            match map.get(&ch) {
+                Some(i) => {
+                    left = max(left, *i + 1);
+                }
+                None => {}
+            }
+            map.insert(*ch, index);
+            ans = max(ans, (index - left + 1) as i32);
+        }
+        ans
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3() {
+        assert_eq!(
+            Solution::length_of_longest_substring(String::from("abcabcbb")),
+            3
+        );
+        assert_eq!(
+            Solution::length_of_longest_substring(String::from("bbbbb")),
+            1
+        );
+        assert_eq!(
+            Solution::length_of_longest_substring(String::from("pwwkew")),
+            3
+        );
+        assert_eq!(
+            Solution::length_of_longest_substring(String::from("abba")),
+            2
+        );
+    }
+}