20241002 finished.

src/problem/mod.rs

@@ -252,3 +252,4 @@ mod p2286_booking_concert_tickets_in_groups;
 mod p2073_time_needed_to_buy_tickets;
 mod p1845_seat_reservation_manager;
 mod p983_minimum_cost_for_tickets;
+mod p1870_minimum_speed_to_arrive_on_time;

src/problem/p1870_minimum_speed_to_arrive_on_time.rs

@@ -0,0 +1,66 @@
+/**
+ * [1870] Minimum Speed to Arrive on Time
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn min_speed_on_time(dist: Vec<i32>, hour: f64) -> i32 {
+        let n = dist.len();
+
+        if hour <= (n - 1) as f64 {
+            return -1;
+        }
+
+        let max_speed = (*dist.iter().max().unwrap()).max(
+            ((dist[n - 1] as f64) / (hour - (n - 1) as f64)).ceil() as i32
+        );
+
+        let check = |v: i32| -> bool {
+            let mut time = 0;
+            for i in 0..n - 1 {
+                time += if dist[i] % v == 0 {
+                    dist[i] / v
+                } else {
+                    dist[i] / v + 1
+                };
+            }
+
+            let time = time as f64 + dist[n - 1] as f64 / v as f64;
+
+            time <= hour
+        };
+
+        let (mut left, mut right) = (1, max_speed);
+
+        while left < right {
+            let middle = (left + right) / 2;
+
+            if check(middle) {
+                right = middle;
+            } else {
+                left = middle + 1;
+            }
+        }
+
+        right
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1870() {
+        assert_eq!(-1, Solution::min_speed_on_time(vec![1, 1], 1.0));
+        assert_eq!(10_000_000, Solution::min_speed_on_time(vec![1, 1, 100_000], 2.01));
+        assert_eq!(1, Solution::min_speed_on_time(vec![1, 3, 2], 6f64));
+        assert_eq!(3, Solution::min_speed_on_time(vec![1, 3, 2], 2.7));
+        assert_eq!(-1, Solution::min_speed_on_time(vec![1, 3, 2], 1.9));
+    }
+}