add cf round-1087-{A,B,C}.rs

storage/cf/rs/round-1087-C.rs

@@ -0,0 +1,54 @@
+use std::io::{Write, stdin, stdout};
+
+fn client(n: usize) {
+    let mut line = String::new();
+    for i in 0..n - 1 {
+        let left = 2 * i + 1;
+        let right = 2 * i + 2;
+
+        println!("? {} {}", left, right);
+        stdout().flush().unwrap();
+        line.clear();
+        stdin().read_line(&mut line).unwrap();
+        let q = line.trim().parse::<usize>().unwrap();
+        if q == 1 {
+            println!("! {}", left);
+            stdout().flush().unwrap();
+            return;
+        }
+    }
+
+    println!("? {} {}", 2 * n - 1, 2 * n - 2);
+    stdout().flush().unwrap();
+    line.clear();
+    stdin().read_line(&mut line).unwrap();
+    let q = line.trim().parse::<usize>().unwrap();
+    if q == 1 {
+        println!("! {}", 2 * n - 1);
+        stdout().flush().unwrap();
+        return;
+    }
+    println!("? {} {}", 2 * n - 1, 2 * n - 3);
+    stdout().flush().unwrap();
+    line.clear();
+    stdin().read_line(&mut line).unwrap();
+    let q = line.trim().parse::<usize>().unwrap();
+    if q == 1 {
+        println!("! {}", 2 * n - 1);
+        stdout().flush().unwrap();
+        return;
+    }
+    println!("! {}", 2 * n);
+}
+
+fn main() {
+    let mut line = String::new();
+    stdin().read_line(&mut line).unwrap();
+    let t = line.trim().parse::<usize>().unwrap();
+    (0..t).for_each(|_| {
+        line.clear();
+        stdin().read_line(&mut line).unwrap();
+        let n = line.trim().parse::<usize>().unwrap();
+        client(n);
+    });
+}