past202109 l

past202109-open/src/bin/l.rs

@@ -1,10 +1,34 @@
-use proconio::{input, marker::Usize1};
+use proconio::input;
+use superslice::Ext;
 
 fn main() {
     input! {
         n: usize,
-        a: [Usize1; n],
+        k: usize,
+        a: [i64; n],
     };
-    let ans = n - a.len();
+    let mut s = std::iter::once(0)
+        .chain(a.iter().scan(0, |acc, &i| {
+            *acc += i;
+            Some(*acc)
+        }))
+        .collect::<Vec<i64>>();
+    s.sort();
+
+    let mut ng = -1_i64;
+    let mut ok = 1 << 60;
+    while ok - ng > 1 {
+        let x = ng + (ok - ng) / 2;
+        let mut count = 0;
+        for (i, s_i) in s.iter().copied().enumerate() {
+            count += s[i + 1..].upper_bound(&(s_i + x));
+        }
+        if count >= k {
+            ok = x;
+        } else {
+            ng = x;
+        }
+    }
+    let ans = ok;
     println!("{}", ans);
 }