Add a sample code for I - Number of Substrings

Author: TonalidadeHidrica

examples/practice2_i_number_of_substrings.rs

@@ -0,0 +1,16 @@
+use ac_library_rs::{lcp_array, suffix_array};
+use std::io::Read;
+use std::iter;
+
+fn main() {
+    let mut s = String::new();
+    std::io::stdin().read_to_string(&mut s).unwrap();
+    let s = s.trim();
+    let suffix_array = suffix_array(s);
+    let ans: u64 = iter::once(0)
+        .chain(lcp_array(s, &suffix_array))
+        .zip(suffix_array)
+        .map(|(c, i)| (s.len() - i - c) as u64)
+        .sum();
+    println!("{}", ans);
+}