java算法--字符组合排序

 

题目:用1、2、2、3、4、5这六个数字，用java写一个main函数，打印出所有不同的排列，如：512234、412345等，要求："4"不能在第三位，"3"与"5"不能相连。

 

不是特别难的题目，暴力算和用图论算（深度遍历）都可以，结果是198.图论的话就是构造无向图，然后深度优先递归。

 

 

package com.graphic;import java.util.Iterator;import java.util.TreeSet;public class CharSequence {private String[] c = {"1","2","2","3","4","5"};private int n = c.length;private boolean[] visited = new boolean[n];private int[][] g = new int[n][n];private TreeSet<String> ts = new TreeSet<String>();private String result = "";public CharSequence(){for(int i=0; i<n; i++){for(int j=0; j<n; j++){if(i == j) g[i][j] = 0;else g[i][j] = 1;}}g[3][5] = 0;g[5][3] = 0;}public void depthFirst(int index){visited[index] = true;result += c[index];if(result.length() == n){ts.add(result);result = result.substring(0,result.length()-1);visited[index] = false;}else{for(int i=0; i<n; i++){if(!visited[i] && g[index][i] == 1){depthFirst(i);}else continue;}result = result.substring(0,result.length()-1);visited[index] = false;}}public void graphicGet(){for(int i=0; i<c.length; i++){depthFirst(i);}int count = 0;System.out.print("图论的结果：");Iterator<String> it = ts.iterator();while(it.hasNext()){String tmp = it.next();if(tmp.contains("35")) continue;if(tmp.contains("53")) continue;if(tmp.charAt(3) == '4') continue;System.out.println(tmp);count++;}System.out.println("共计："+count+"个");}public void bruteForce(){System.out.println("暴力搜的结果：");int count = 0;for(int i = 122345; i<543222; i++){String tmp = ""+i;if(tmp.charAt(3) == '4') continue;if(tmp.contains("35")) continue;if(tmp.contains("53")) continue;if(tmp.contains("5") && tmp.contains("4") && tmp.contains("3") && tmp.contains("1")){int index = tmp.indexOf("2");if(index == -1) continue;if(index == tmp.length()-1) continue;if(tmp.substring(index+1).contains("2")){System.out.println(tmp); count++;}}}System.out.print("共计："+count+"个");}public void recrusive(){}public static void main(String[] args) {CharSequence cs = new CharSequence();//图论的方法cs.graphicGet();//暴力搜索cs.bruteForce();}}