只要不比前一个数大1，区间总数就加1

只要不比前一个数大1，区间总数就加1：

import java.util.*;
public class Main {
    public static void main(String[] args) throws Exception{
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(), r = 1;
        int[] v = new int[n];
        for(int i = 0; i < n; ++i) v[i] = sc.nextInt();
        for(int i = 1; i < n; ++i){
            if(v[i] != v[i - 1] + 1) r++;
        }
        System.out.println(r);
    }
}