Merge pull request #3257 from saurabh10041998/find-anagrams

Create 0438-find-all-anagrams-in-a-string.rs

Author: Ykhan799

Diff for: rust/0438-find-all-anagrams-in-a-string.rs

@@ -0,0 +1,65 @@
+use std::ops::{Index, IndexMut};
+struct CharVec(Vec<i32>);
+
+impl CharVec {
+    fn new() -> Self {
+        Self(vec![0; 26])
+    }
+}
+
+impl Index<char> for CharVec {
+    type Output = i32;
+    fn index(&self, index: char) -> &Self::Output {
+        match index {
+            'a'..='z' => &self.0[(index as u8 - 'a' as u8) as usize],
+            _ => panic!("[!!] {} character is not supported in CharVec", index),
+        }
+    }
+}
+
+impl IndexMut<char> for CharVec {
+    fn index_mut(&mut self, index: char) -> &mut Self::Output {
+        match index {
+            'a'..='z' => &mut self.0[(index as u8 - 'a' as u8) as usize],
+            _ => panic!("[!!] {} character is not supported in CharVec", index),
+        }
+    }
+}
+
+impl Eq for CharVec {}
+
+impl PartialEq for CharVec {
+    fn eq(&self, other: &Self) -> bool {
+        self.0.eq(&other.0)
+    }
+}
+
+impl Solution {
+    pub fn find_anagrams(s: String, p: String) -> Vec<i32> {
+        let (s_len, p_len) = (s.len(), p.len());
+        let mut ans = vec![];
+        if s_len < p_len {
+            return ans;
+        }
+        let mut freq_s = CharVec::new();
+        let mut freq_p = CharVec::new();
+        let s = s.chars().collect::<Vec<char>>();
+        let p = p.chars().collect::<Vec<char>>();
+        for i in 0..p_len {
+            freq_s[s[i]] += 1;
+            freq_p[p[i]] += 1;
+        }
+        if freq_s == freq_p {
+            ans.push(0);
+        }
+        /* sliding window with of length p_len */
+        for i in p_len..s_len {
+            freq_s[s[i - p_len]] -= 1;
+            freq_s[s[i]] += 1;
+            if freq_s == freq_p {
+                ans.push((i - p_len + 1) as i32);
+            }
+        }
+        ans
+    }
+}