20240328 Finished

src/problem/mod.rs

@@ -87,3 +87,4 @@ mod p322_coin_change;
 mod p518_coin_change_ii;
 mod p2642_design_graph_with_shortest_path_calculator;
 mod p2580_count_ways_to_group_overlapping_ranges;
+mod p1997_first_day_where_you_have_been_in_all_the_rooms;

src/problem/p1997_first_day_where_you_have_been_in_all_the_rooms.rs

@@ -0,0 +1,39 @@
+/**
+ * [1997] First Day Where You Have Been in All the Rooms
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn first_day_been_in_all_rooms(next_visit: Vec<i32>) -> i32 {
+        let m = 1_000_000_007;
+        let mut dp = vec![0;next_visit.len()];
+        dp[0] = 2;
+
+        for i in 1..next_visit.len() {
+            let next = next_visit[i] as usize;
+
+            dp[i] = dp[i - 1] + 2;
+
+            if next != 0 {
+                dp[i] = (dp[i] - dp[next - 1] + m) % m;
+            }
+            dp[i] = (dp[i] + dp[i - 1]) % m;
+        }
+
+        dp[next_visit.len() - 2]
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1997() {
+    }
+}