20241222 finished.

src/problem/mod.rs

@@ -384,3 +384,5 @@ mod p3285_find_indices_of_stable_mountains;
 mod p3138_minimum_length_of_anagram_concatenation;
 
 mod p2545_sort_the_students_by_their_kth_score;
+
+mod p1387_sort_integers_by_the_power_value;

src/problem/p1387_sort_integers_by_the_power_value.rs

@@ -0,0 +1,64 @@
+/**
+ * [1387] Sort Integers by The Power Value
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn get_kth(lo: i32, hi: i32, k: i32) -> i32 {
+        let mut memo = HashMap::new();
+        memo.insert(1, 0);
+
+        let mut array: Vec<(i32, i32)> =
+            (lo..=hi).map(|x| (Self::search(x, &mut memo), x)).collect();
+        array.sort_unstable();
+
+        array[k as usize - 1].1
+    }
+
+    fn search(x: i32, memo: &mut HashMap<i32, i32>) -> i32 {
+        if let Some(&result) = memo.get(&x) {
+            return result;
+        }
+
+        let result = if x % 2 == 0 {
+            Self::search(x / 2, memo) + 1
+        } else {
+            Self::search((x * 3 + 1) / 2, memo) + 2
+        };
+
+        memo.insert(x, result);
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_search() {
+        let mut memo = HashMap::new();
+        memo.insert(1, 0);
+
+        assert_eq!(16, Solution::search(7, &mut memo));
+        assert_eq!(3, Solution::search(8, &mut memo));
+        assert_eq!(19, Solution::search(9, &mut memo));
+        assert_eq!(6, Solution::search(10, &mut memo));
+        assert_eq!(14, Solution::search(11, &mut memo));
+        assert_eq!(9, Solution::search(12, &mut memo));
+        assert_eq!(9, Solution::search(13, &mut memo));
+        assert_eq!(17, Solution::search(14, &mut memo));
+        assert_eq!(17, Solution::search(15, &mut memo));
+    }
+
+    #[test]
+    fn test_1387() {
+        assert_eq!(13, Solution::get_kth(12, 15, 2));
+        assert_eq!(7, Solution::get_kth(7, 11, 4));
+    }
+}