Question

How to find the shortest identical consecutive sublist in a list with Java

Answer 1

import java.util.List; 
import java.util.Arrays; 
import java.util.Collections; 
  
public class ShortestRunProgram {
     
    public static List<Integer> shortest_identical_consecutive_sublist(List<Integer> lst) {
        if (lst.isEmpty()) return Collections.emptyList();
  
        int bestStart = 0;
        int bestLen = lst.size();
  
        int currentStart = 0;
        int currentLen = 1;
  
        for (int i = 1; i < lst.size(); i++) {
            if (lst.get(i).equals(lst.get(i - 1))) {
                currentLen++;
            } else {
                if (currentLen < bestLen) {
                    bestLen = currentLen;
                    bestStart = currentStart;
                }
                currentStart = i;
                currentLen = 1;
            }
        }
  
        if (currentLen < bestLen) {
            bestLen = currentLen;
            bestStart = currentStart;
        }
  
        return lst.subList(bestStart, bestStart + bestLen);
    }
  
    // ------------------------------------------------------------
    // MAIN PROGRAM
    // ------------------------------------------------------------
    public static void main(String[] args) {
  
        List<Integer> lst = Arrays.asList(3,3,3, 7,7,7,7,7, 2,2, 5,5,5,5, 9,9,9,9,9,9);
  
        List<Integer> resultList = shortest_identical_consecutive_sublist(lst);
        System.out.print("List result: ");
        for (int x : resultList) System.out.print(x + " ");
    }
}
  
  
/*
run:
  
List result: 2 2 
  
*/

 

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