Divide and conquer algorithm explanation and application

Divide and Conquer Algorithm

The basic steps divide and conquer algorithm

@author:qyx            2013/6/3

Partition method has three steps on each recursion level

1) Decomposition: the original problem into several smaller, independent of each other, the same as the original problem in the form of sub-problems

2) Solution: If a smaller sub-problems to be solved rather easily scale the direct solution, or solutions of each sub-problems recursively

3) merger: the merger of each sub-problem solution for the original problem solution

 

Tower of Hanoi algorithm uses divide and conquer the problem:

Solving process can be divided into three steps:

If there is a disk 1 A-> C

2 If the plate number more than two, we always can be seen as two disks, one lowermost plate, top plate 2

1) the uppermost first disc A-> B

2) The lowermost disc A-> C

3) all the discs from column B B-> C

package com.qyx.dac;

public class Hanoitower {
    public static void main(String[] args) {
        hanoitower(5, 'A', 'B', 'C');
    }
    // Tower of Hanoi moving method
     // use the divide and conquer algorithm 
    public  static  void hanoitower ( int NUM, char A, char B, char C)
    {
        // If only one disk 
        IF (NUM == 1 )
        {
            System.out.println ( "first disk from the" A + + "->" + C);
        } The else {
             // if the number of discs is greater than 2, then I can be seen two discs: a lowermost disc above the disc 2
             // 1 uppermost first disc A-> B, during the mobile use to C 
            hanoitower (. 1-NUM , a, C, B);
             // 2 the most bottom disc A-> C 
            System.out.println ( "first" + num + "disks from" + a + "->" + C);
             // . 3 B all discs from the column using B-> C, the process moves to a column 
            hanoitower (-NUM. 1 , B, a, C);
            
        }
    }
}