Untitled

impl Solution {
  pub fn min_window(s: String, t: String) -> String {
    let mut freq = vec![0; 128];
    for b in t.bytes() { freq[b as usize] += 1; }
    let (mut i, mut r, mut c) = (0, 0..0, t.len());
    for (j, b) in s.bytes().enumerate() {
      if freq[b as usize] > 0 { c -= 1; }
      freq[b as usize] -= 1;
      while c == 0 {
        if j - i + 1 < r.len() || r.len() == 0 { r = i..j + 1; }
        let a = s.as_bytes()[i] as usize;
        freq[a] += 1; if freq[a] > 0 { c += 1; }
        i += 1;
      }
    }
    s[r].into()
  }
}