Day 002-Sequential Digits

//  ( ---- https://leetcode.com/problems/sequential-digits/ ---- )

//  (--- 1291. SEQUENTIAL DIGITS ---)


class Solution {
    public List<Integer> sequentialDigits(int low, int high) {
      List<Integer> ans=new ArrayList();
        int size_of_sequence = 8;          // no. of loops runs 
        int incrementer = 11;              // output is like 123 , 234 , 456 (234 - 123)=111 ; (456 - 234)=111 ;    
        int sequencial_digit = 1;          // current no. (assume)     
        while(incrementer < high)
        {
            int initial_sequencial_digit = sequencial_digit; 
            for(int i = 1; i <= size_of_sequence; i++)
            {
                sequencial_digit += incrementer;  
                if(sequencial_digit >= low && sequencial_digit <=high)       // if condination false then go to line 21 
                    ans.add(sequencial_digit);
            }
            sequencial_digit = incrementer + initial_sequencial_digit;
            incrementer = incrementer*10+1;
            size_of_sequence--;
        }
        return ans;
    }    
}

// Example :-- (Low = 100 and high = 300)  output =[123 , 234]

//  (----Another way----) 

// class Solution {
//     public List<Integer> sequentialDigits(int low, int high) {
//        int start = 1, cur = 1, inc = 11, t = 8;
//         List<Integer> ans = new ArrayList<>();
//         while(cur <= high){
//             for (int i = 0; i < t; i++){
//                 cur += inc;
//                 if (cur >= low && cur <= high) {
//                     ans.add(cur);
//                 }
//             }
//             inc = 10 * inc + 1;
//             start = 10 * start + 10 - t;
//             cur = start;
//             t--;
//         } 
//         return ans;
//     } 
// }