How Monkeys climb steps

Monkey steps:

A monkey is very naughty and likes to climb steps. But because the monkey is too small, it can only climb one or two steps in one step. Calculate all possible crawling paths of the monkey.

package shuai.study.steps;import java.util.ArrayList;import java.util.HashSet;import java.util.Iterator;import java.util.List;import java.util.Set;/** * @author shengshu *  */public class MonkeyCrawl {// Get paths, which will be permutatedpublic static Set<String> getPathsSet(int steps) {Set<String> pathsSet = new HashSet<String>();for (int i = 0; i <= steps / 2; i++) {int twoStepSum = i * 2;int oneStepTimes = steps - twoStepSum;StringBuffer pathStringBuffer = new StringBuffer();for (int x = 0; x < oneStepTimes; x++) {// "-" represent one steppathStringBuffer.append("-");}for (int y = 0; y < i; y++) {// "=" represent two stepspathStringBuffer.append("=");}pathsSet.add(pathStringBuffer.toString());}return pathsSet;}// Permutate all possible pathspublic static void permutatePaths(String path, List<String> list) {if (path.length() == 1) {for (int i = 0; i < list.size(); i++) {System.out.print(list.get(i));}System.out.println(path);} else {int index[] = new int[path.length()];for (int i = 0; i < index.length; i++) {index[i] = path.indexOf(path.charAt(i));}for (int i = 0; i < path.length(); i++) {String subPath = path.substring(1, path.length());if (i == index[i]) {list.add("" + path.charAt(0));permutatePaths(subPath, list);list.remove(list.size() - 1);}path = subPath + path.charAt(0);}}}public static void main(String[] args) {// Set steps as 15, or othersSet<String> pathsSet = MonkeyCrawl.getPathsSet(15);Iterator<String> iterator = pathsSet.iterator();while (iterator.hasNext()) {String path = iterator.next();MonkeyCrawl.permutatePaths(path, new ArrayList<String>());}}}

How Monkeys climb steps