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  1. public class Main {
  2.  
  3.        static int stack[] = new int[100],
  4.            n,
  5.            level;
  6.  
  7.        public static void init() {
  8.             stack[level] = -1;
  9.        }
  10.  
  11.        public static boolean valid() {return true;}
  12.  
  13.        public static boolean succ() {
  14.  
  15.            if(stack[level]<1){
  16.              stack[level]++;
  17.              return true;
  18.            }
  19.            return false;
  20.        }
  21.  
  22.        public static boolean sol() {
  23.          return (level == n);
  24.        }
  25.  
  26.        public static void main(String args[]) {
  27.            n = 3;
  28.            bk();
  29.        }
  30.  
  31.        public static void bk() {
  32.           level = 1;
  33.           boolean s,v;
  34.           init();
  35.           while(level>0){
  36.             s = true;
  37.             v = false;
  38.             while(s && !v){
  39.               s = succ();
  40.               if(s) v = valid();
  41.             }
  42.             if(s) {
  43.              if(sol())print();
  44.              else{
  45.                level++;init();
  46.              }
  47.             }else{
  48.               level--;
  49.             }
  50.           }
  51.        }
  52.  
  53.        public static void print() {
  54.  
  55.          for(int i = 1; i <= n; ++i){
  56.            if(stack[i] == 1) {
  57.              System.out.print(i + " ");
  58.            }
  59.          }
  60.          System.out.println("\n");
  61.        }
  62. }
  63.  
Success #stdin #stdout 0.09s 55608KB
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Standard input is empty
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3 

2 

2 3 

1 

1 3 

1 2 

1 2 3
https://ideone.com/QPCyH4
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language:
Java (HotSpot 12)
created:
149 days ago
visibility:
secret

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