count substrings

jhideki · jhideki · commit 18fbd561bfdd · 2024-06-21T16:37:23.000-07:00
diff --git a/src/main.rs b/src/main.rs
@@ -1,2 +1,2 @@
-mod longest_palindromic;
+mod palindromic_substrings;
 fn main() {}
diff --git a/src/palindromic_substrings.rs b/src/palindromic_substrings.rs
@@ -0,0 +1,23 @@
+pub struct Solution {}
+impl Solution {
+    pub fn count_substrings(s: String) -> i32 {
+        let s = s.as_bytes();
+        let mut res = 0;
+        for i in 0..s.len() {
+            let (l, mut r) = (i as i32, i as i32);
+            res += Self::count(s, l, r);
+            r += 1;
+            res += Self::count(s, l, r);
+        }
+        res
+    }
+    fn count(s: &[u8], mut l: i32, mut r: i32) -> i32 {
+        let mut res = 0;
+        while l >= 0 && r < s.len() as i32 && s[l as usize] == s[r as usize] {
+            res += 1;
+            l -= 1;
+            r += 1;
+        }
+        res
+    }
+}
