unable to find out why frontier nodes are oscillating

This code is an implementation of frontier exploration.

code - https://drive.google.com/drive/folders/0B3_gyQ1dIf-QTHE1VnozeXJxQnM

download the code. run configure.m in matlab. Then - When you run the demo ( greedy_rhcp_sensor.m in navpadfork/demo/rhcp) , you will notice that the robot jumps from one unexplored frontier to the other, oscillating back and forth. How do I change the way frontier nodes are selected to remove this oscillatory behavior?