add 1387

fishercoder1534 · fishercoder1534 · commit 7aa0d60e3ff5 · 2020-03-21T09:39:14.000-07:00
diff --git a/README.md b/README.md
@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ &#9733;
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
+|1387|[Sort Integers by The Power Value](https://leetcode.com/problems/sort-integers-by-the-power-value/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1387.java) | |Medium|Sort, Graph|
 |1386|[Cinema Seat Allocation](https://leetcode.com/problems/cinema-seat-allocation/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1386.java) | |Medium|Array, Greedy|
 |1385|[Find the Distance Value Between Two Arrays](https://leetcode.com/problems/find-the-distance-value-between-two-arrays/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1385.java) | |Easy|Array|
 |1382|[Balance a Binary Search Tree](https://leetcode.com/problems/balance-a-binary-search-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1382.java) | |Medium|Binary Search Tree|
diff --git a/src/main/java/com/fishercoder/solutions/_1387.java b/src/main/java/com/fishercoder/solutions/_1387.java
@@ -0,0 +1,76 @@
+package com.fishercoder.solutions;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * 1387. Sort Integers by The Power Value
+ *
+ * The power of an integer x is defined as the number of steps needed to transform x into 1 using the following steps:
+ * if x is even then x = x / 2
+ * if x is odd then x = 3 * x + 1
+ *
+ * For example, the power of x = 3 is 7 because 3 needs 7 steps to become 1 (3 --> 10 --> 5 --> 16 --> 8 --> 4 --> 2 --> 1).
+ * Given three integers lo, hi and k. The task is to sort all integers in the interval [lo, hi] by the power value in ascending order, if two or more integers have the same power value sort them by ascending order.
+ * Return the k-th integer in the range [lo, hi] sorted by the power value.
+ * Notice that for any integer x (lo <= x <= hi) it is guaranteed that x will transform into 1 using these steps and that the power of x is will fit in 32 bit signed integer.
+ *
+ * Example 1:
+ * Input: lo = 12, hi = 15, k = 2
+ * Output: 13
+ * Explanation: The power of 12 is 9 (12 --> 6 --> 3 --> 10 --> 5 --> 16 --> 8 --> 4 --> 2 --> 1)
+ * The power of 13 is 9
+ * The power of 14 is 17
+ * The power of 15 is 17
+ * The interval sorted by the power value [12,13,14,15]. For k = 2 answer is the second element which is 13.
+ * Notice that 12 and 13 have the same power value and we sorted them in ascending order. Same for 14 and 15.
+ *
+ * Example 2:
+ * Input: lo = 1, hi = 1, k = 1
+ * Output: 1
+ *
+ * Example 3:
+ * Input: lo = 7, hi = 11, k = 4
+ * Output: 7
+ * Explanation: The power array corresponding to the interval [7, 8, 9, 10, 11] is [16, 3, 19, 6, 14].
+ * The interval sorted by power is [8, 10, 11, 7, 9].
+ * The fourth number in the sorted array is 7.
+ *
+ * Example 4:
+ * Input: lo = 10, hi = 20, k = 5
+ * Output: 13
+ *
+ * Example 5:
+ * Input: lo = 1, hi = 1000, k = 777
+ * Output: 570
+ *
+ * Constraints:
+ * 1 <= lo <= hi <= 1000
+ * 1 <= k <= hi - lo + 1
+ * */
+public class _1387 {
+    public static class Solution1 {
+        public int getKth(int lo, int hi, int k) {
+            List<int[]> power = new ArrayList<>();
+            for (int i = lo; i <= hi; i++) {
+                power.add(new int[]{getSteps(i), i});
+            }
+            Collections.sort(power, (a, b) -> a[0] != b[0] ? a[0] - b[0] : a[1] - b[1]);
+            return power.get(k - 1)[1];
+        }
+
+        private int getSteps(int number) {
+            int steps = 0;
+            while (number != 1) {
+                if (number % 2 == 0) {
+                    number /= 2;
+                } else {
+                    number = 3 * number + 1;
+                }
+                steps++;
+            }
+            return steps;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_1387Test.java b/src/test/java/com/fishercoder/_1387Test.java
@@ -0,0 +1,31 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1387;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _1387Test {
+    private static _1387.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1387.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(13, solution1.getKth(12, 15, 2));
+    }
+
+    @Test
+    public void test2() {
+        assertEquals(1, solution1.getKth(1, 1, 1));
+    }
+
+    @Test
+    public void test3() {
+        assertEquals(7, solution1.getKth(7, 11, 4));
+    }
+}
