Constructing Bridges Problem

Constructing Bridges: 
A River that cuts through a set of cities above and below it. Each city above the river is matched with a city below the river. 
Construct as many Non-Crossing Bridges as possible. 
Input: 
Above Bank >> 7 4 3 6 2 1 5 
Below Bank >> 5 3 2 4 6 1 7 
are given in pairs: (7,5) (4,3) (3,2) (6,4) (2,6) (1,1) (5,7) 
Output: 
(1,1) (3,2) (4,3) (6,4) (7,5)



Solution
------------


import java.util.HashMap;
import java.util.Map;


/**
 * @author shashi
 *
 **/
public class RiverBridge {

public static void main(String []args)
{
//get the above and below banks
int aboveBank[]={7 ,4, 3, 6, 2, 1, 5};
int belowBank[]={ 5, 3, 2, 4, 6, 1, 7};

//now create a Map for storing Pairs
Map<Integer, Integer> myMap=new HashMap<Integer, Integer>();
//base condition
if(aboveBank.length !=belowBank.length)
{
//River flow is not correct way
System.out.print("Your river is not flowing in correct way");
}
//if not
for(int i=0;i<aboveBank.length-1;i++)//you can also use below.length
{
if(aboveBank[i]>=belowBank[i])
{
//pair for bridge is founded so add to map
myMap.put(aboveBank[i], belowBank[i]);
}
}
//now print map elements
for(Map.Entry<Integer, Integer> entry:myMap.entrySet())
{
int key=entry.getKey();
int val=entry.getValue();
System.out.print("("+key+","+val+")"+"  " );
}

}
}

output:

-----------

(1,1)  (3,2)  (4,3)  (6,4)  (7,5)