Package g1601_1700.s1643_kth_smallest_instructions

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    1643 - Kth Smallest Instructions\.

    Hard

    Bob is standing at cell (0, 0), and he wants to reach destination: (row, column). He can only travel right and down. You are going to help Bob by providing instructions for him to reach destination.

    The instructions are represented as a string, where each character is either:

    • 'H', meaning move horizontally (go right ), or

    • 'V', meaning move vertically (go down ).

    Multiple instructions will lead Bob to destination. For example, if destination is (2, 3), both "HHHVV" and "HVHVH" are valid instructions.

    However, Bob is very picky. Bob has a lucky number k, and he wants the <code>k<sup>th</sup></code> lexicographically smallest instructions that will lead him to destination. k is 1-indexed.

    Given an integer array destination and an integer k, return the <code>k<sup>th</sup></code> lexicographically smallest instructions that will take Bob to destination.

    Example 1:

    Input: destination = 2,3, k = 1

    Output: "HHHVV"

    Explanation: All the instructions that reach (2, 3) in lexicographic order are as follows: "HHHVV", "HHVHV", "HHVVH", "HVHHV", "HVHVH", "HVVHH", "VHHHV", "VHHVH", "VHVHH", "VVHHH".

    Example 2:

    Input: destination = 2,3, k = 2

    Output: "HHVHV"

    Example 3:

    Input: destination = 2,3, k = 3

    Output: "HHVVH"

    Constraints:

    • destination.length == 2

    • 1 &lt;= row, column &lt;= 15

    • 1 &lt;= k &lt;= nCr(row + column, row), where nCr(a, b) denotes a choose b.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final String kthSmallestPath(IntArray destination, Integer k)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait