【Java每日一题，容器+暴力优化】csp202109-2 非零段划分

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import java.util.Collection;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.TreeMap;
public class Main {
    public static void main(String[] args) {
        Scanner s=new Scanner(System.in);
        int n=s.nextInt();
        int[] arr=new int[n+2];
        TreeMap<Integer, LinkedList<Integer>> treeMap=new TreeMap();
        for(int i=1;i<=n;i++){
            arr[i]=s.nextInt();
            if(arr[i]!=0){
                if(!treeMap.containsKey(arr[i])){
                    LinkedList<Integer> linkedList=new LinkedList();
                    linkedList.add(i);
                    treeMap.put(arr[i],linkedList);
                }else {
                    treeMap.get(arr[i]).add(i);
                }
            }
        }
        int count=0;
        for(int i=1;i<=n;i++){
            if(arr[i+1]==0&&arr[i]!=0){
                count++;
            }
        }
        int max=count;
        Collection<LinkedList<Integer>> lists = treeMap.values();
        for(LinkedList<Integer> list:lists){
            for(int index:list){
                arr[index]=0;
                if(arr[index-1]==0&&arr[index+1]==0){
                    count--;
                }else if(arr[index+1]!=0&&arr[index-1]!=0) {
                    count++;
                }
            }
            max= Math.max(max,count);
        }
        System.out.println(max);
    }
}