Poj Solution 1146

http://poj.org/problem?id=1146

/* @author:zeropinzuo */
import java.io.*;
import java.util.*;

public class Main{
 static Scanner cin;
 public static void main(String args[]){
    cin = new Scanner(System.in);
    while(run(cin.next()))
                ;
}

static boolean run(String input){
    if(input.compareTo("#") == 0)
        return false;
    
    System.out.println(next(input));
    return true;
}

static String next(String s){
    char[] map = s.toCharArray();

    int count = map.length-1;

    while(count>0){
         if(map[count-1] < map[count])
        break;
      count--;
    }    

    if(count==0)
      return "No Successor";
        
    char node = map[count];
    int position = count;
    for(int i=count;i< map.length;i++)
      if((map[i]>map[count-1])&&(map[i]< node)){
            node = map[i];
            position = i;
      }

    map[position] = map[count-1];
    map[count-1]  = node;

    PriorityQueue< Char> heap = new PriorityQueue< Char>();
    for(int i=count;i< map.length;i++)
        heap.add(new Char(map[i]));

    for(int i=count;i< map.length;i++)
        map[i] = heap.poll().c;

    return new String(map);

  }

}

class Char implements Comparable{
 char c;

 public Char(char c){
    this.c = c;
 }
 public int compareTo(Object o){
    Char another = (Char)o;
    return this.c-another.c;
 }
}