LeetCode-in-Rust
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:
0 <= s.length <= 5 * 104sconsists of English letters, digits, symbols and spaces.
Solution
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
}
}