complete 4674.rs 9912.rs 10826.rs 12140.rs 14452.rs 17021.rs 17386.rs 20929.rs

storage/zeta/rs/completed/4674.rs

@@ -0,0 +1,51 @@
+use std::io::stdin;
+
+fn convert(text: Vec<char>) -> Vec<u64> {
+    text.into_iter()
+        .map(|x| match x {
+            '_' => 0,
+            'a'..='z' => (x as u8 - 'a' as u8 + 1) as u64,
+            '.' => 27,
+            _ => u64::MAX,
+        })
+        .collect()
+}
+
+fn revert(code: Vec<u64>) -> Vec<char> {
+    code.into_iter()
+        .map(|x| match x {
+            0 => '_',
+            1..=26 => (b'a' + x as u8 - 1) as char,
+            27 => '.',
+            _ => '*',
+        })
+        .collect()
+}
+
+fn decrypt(k: u64, ciphertext: Vec<char>) -> Vec<char> {
+    let n = ciphertext.len();
+    let ciphercode = convert(ciphertext);
+    let mut plaincode = vec![0u64; n];
+
+    for i in 0..n {
+        let j = ((k * i as u64) % n as u64) as usize;
+        plaincode[j] = ((ciphercode[i] as u64 + i as u64) % 28) as u64;
+    }
+    revert(plaincode)
+}
+
+fn main() {
+    let mut line = String::new();
+
+    loop {
+        line.clear();
+        stdin().read_line(&mut line).unwrap();
+        if line.starts_with("0") {
+            break;
+        }
+        let mut iter = line.split(' ');
+        let k = iter.next().unwrap().trim().parse::<u64>().unwrap();
+        let msg = iter.next().unwrap().trim().chars().collect();
+        println!("{}", decrypt(k, msg).into_iter().collect::<String>());
+    }
+}