n个数分m组

package wordcount.n个数分m组;

import java.util.ArrayList;
import java.util.List;

public class FenMain {
    static int[] arr;
    static int[] vis;
    static int n=6;
    static int m=3;
    public static void main(String[] args) {
        arr = new int[n];
        for (int i = 0; i < n; ++i) {
            arr[i] = i;
        }
        List<Integer>[] lists = new List[m];
        for (int i = 0; i < m; ++i) {
            lists[i] = new ArrayList<>();
        }
        vis = new int[n];

        dfs(lists,0 ,0 );
    }

    public static void dfs(List<Integer>[] lists, int currM,int count) {
        if(count==arr.length) {
            if(currM==m){
                System.out.println("============");
                for(int i=0;i<lists.length;++i){
                    for(Integer x:lists[i]){
                        System.out.print(arr[x]+",");
                    }
                    System.out.println();
                }
            }
        }

        if(currM>=m) return;
        if (lists[currM].size() == 0) {
            Integer firstIndex = getFirstIndex(vis);
            if(firstIndex==null) return;
            vis[firstIndex] = 1;
            lists[currM].add(firstIndex);

            dfs(lists, currM,count+1);
            if(currM<=m) {
                dfs(lists, currM + 1, count + 1);
            }

            lists[currM].remove(lists[currM].size() - 1);
            vis[firstIndex] = 0;
        } else {

            for(int i=lists[currM].get(lists[currM].size() - 1) + 1;i<n;++i){
                if(vis[i]==0) {
                    vis[i] = 1;
                    lists[currM].add(i);

                    dfs(lists, currM, count + 1);
                    if (currM <= m) {
                        dfs(lists, currM + 1, count + 1);
                    }
                    lists[currM].remove(lists[currM].size() - 1);
                    vis[i] = 0;
                }
            }
        }
    }



    private static Integer getFirstIndex(int[] vis) {
        for (int i = 0; i < vis.length; ++i) {
            if (vis[i] == 0) {
                return i;
            }
        }
        return null;
    }

    private static Integer getFirstIndex(int[] vis, int start) {
        for (int i = start; i < vis.length; ++i) {
            if (vis[i] == 0) {
                return i;
            }
        }
        return null;
    }
}