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  1. Practice
  2. Data Structures
  3. Arrays
  4. Dynamic Array
  5. Discussions

Dynamic Array

  • rahulshetty96 + 7 comments

    import java.io.; import java.util.;

    public class Solution {

    public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

    int n = sc.nextInt();
    int q = sc.nextInt();
    int inc=0,inb=0;
    int last = 0,x;
    int  a[][] = new int[q][3];
    int  b[] = new int[100000];
   int  c[] = new int[100000];

    for(int i = 0; i<q ; i++)
    {
        for(int j=0;j<3;j++)
        a[i][j] = sc.nextInt();

        x = ((a[i][1]^last)%n);              //sequence s1 or s0
        if(a[i][0] == 1)                    // query 1 or 0
        {
            if(x == 0)                         
            b[inb++] = a[i][2];
            else
            c[inc++] = a[i][2];
        }
        else{

                if(x == 0)
                last = b[a[i][2]%(inb)];
                else
                last = c[a[i][2]%(inc)];

                System.out.println(last);


        }


    }


}

    }

    WOULD ANYONE MIND HELPING ME TO FIND WHATS WRONG WITH THIS PROGRAM?

    • Murli0802 + 1 comment

      n is number of sequences so ther might possible more then 2 sequences. In that case you need more array like b[],c[].Max possible size of these arrays are q so there you can also save some memory.

      • rahulshetty96 + 1 comment

        Thanks a lot friend!I got my mistake.

        • swaroophople + 1 comment

          I have the same problem can you explain??

          • Murli0802 + 1 comment

            n = number of sequence lastAns=0 q = number of query sequences S0={} S1={} S2={} . . . Sn={}

            for queries type (1) 1 x y index of sequence id = (x^lastAns)%n append y in Si-th sequence

            (2) 2 x y index of sequence id = (x^lastAns)%n lastAns = valueAt(y%(size of Si-th sequence)) and pint lastAns

            after every query value of lastAns will be updated according to query type.

            • anmolnarang4210 + 2 comments

              what is y and x

              • Murli0802 + 2 comments

                y and x are integer inputs (given in question)

                • ankit_1310029 + 3 comments

                  what is the size of every sequence??

                  according to me it must be n, but i'm guessing that size of each sequence should be exactly the amount of elements that are present at that moment.

                  • [deleted] + 1 comment

                    Yes, the sequences start of as size 0 and grow as you add elements in.

                    • Abhi_jit + 0 comments

                      so what should we take the size initially

                  • cemelo + 0 comments

                    Yeah. That sentence has terrible phrasing.

                  • karadeniz + 1 comment

                    Sequence is a dynamic list. in Java Arraylist or in C# List is ok to use i think?

                    • akki1996 + 1 comment

                      Can also use 2D Vector in Cpp

                      • Mikeiyan + 0 comments

                        yes i did it with vectors

                • ankit_1310029 + 0 comments
                  [deleted]
              • muntaqeem + 2 comments

                watch each input line after the first one.

                1 0 5

                this means, query type 1, x is 0 and y is 5

                • 2suprit + 0 comments

                  Thank you so much, understood this now

                • undefitied + 0 comments

                  Thanks! It was unclear.

    • vincent_g + 0 comments
      [deleted]
    • darkcode + 1 comment

      Use ArrayList,it will be easier

      • tiger_1 + 2 comments

        how to create N number of arraylist dynamically ??

        • steffen_vulpius + 1 comment
          ArrayList[] sequenceArray=new ArrayList[length];
for (int j = 0; j <length; j++) {
            sequenceArray[j]=new ArrayList<Integer>();
}

          where length is the first int read from the input.

          • codertoaster + 0 comments

            Or you can just create and ArrayList of ArrayLists.

            ArrayList> arr=new ArrayList<>();

            each element i in the list arr will be another ArrayList.

        • aparnamsh29 + 1 comment

          To avoid errors such as "Unsafe operations",Use the following:-

          ArrayList<ArrayList<Integer>> b=new ArrayList<ArrayList<Integer>>(n);
		for(int i=0;i<n;i++)
			b.add(new ArrayList<Integer>());

          And to later on perform the operations, use expressions like:

          int t=(a[i][1]^last)%n;
b.get(t).add(a[i][2]);
          • dejifab + 0 comments

            You're wonderful for this man

    • serpentsmiles + 1 comment

      Many, many users have repeatedly asked that others not post their code in the discussions. If you wish help with your code, simply say so, and if another user responds yes, then send them a private message. Please.

      • WittyNotes + 1 comment

        Is this really true? I've never seen others comment on this, and it's seems to be a function of the discussion board to post your (working) result and compare to others' solutions.

        • AGRN96 + 0 comments

          I find it much better to just submit your code, then copy the link and posting it on here. It seems to be a way to deter people from just copying the code and not learning anything. The submission link method requires them to forgo any points if they have not completed the problem.

    • rwan7727 + 7 comments

      In c++:

      int n,q;
cin >> n >> q;

vector <vector <int> > s(n,vector <int> ());
int lastAnswer=0;
for (int i=0;i<q;i++) {
    int t,x,y;
    cin >> t >> x >> y;

    if (t==1) {
        s[(x^lastAnswer)%n].push_back(y);
    }
    else {
        lastAnswer=s[(x^lastAnswer)%n][y%s[(x^lastAnswer)%n].size()];
        cout << lastAnswer << endl;
    }
}
      • bhavgothadiya + 1 comment

        Here why vector > s(n,vector ());

        • bhavgothadiya + 0 comments

          what is used here vector>

      • bhavgothadiya + 0 comments

        what is T,X,y Here

      • amorthyo + 0 comments

        Why did you do lastAnswer=s[(x^lastAnswer)%n][y%s[(x^lastAnswer)%n].size()]; in the column sec for s?

      • josepaez_2 + 0 comments

        great approach!

      • aryabharat + 1 comment

        we can make it a bit more simple by replacing vector decl. by

        vector <int> s[n];
        • abhaykuma + 0 comments

          what will that do ? will it declare 2d vector of n rows ?

      • thethanh92 + 0 comments
        [deleted]
      • rohanshenoy96 + 0 comments

        I wrote this and i am getting Run time error. ALmost same code. Can anyone tell me why this isn't working.

        #!/bin/python3

import math
import os
import random
import re
import sys

# Complete the dynamicArray function below.
def dynamicArray(n, queries):
    lastNumber = 0
    seqList=[];
    for i in range(n):
        seqList.append([])
    res = [];
    for k, x, y in queries:
        index = (x^lastNumber)%n
        if k==1:
            seqList[index].append(y)
            print(seqList)
        else:
            size = len(seqList[index])
            print(seqList)
            print(size)
            lastNumber = seqList[index][y%size]
            print(lastNumber)
            res.append(lastNumber)
            
    return res 

if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    nq = input().rstrip().split()

    n = int(nq[0])

    q = int(nq[1])

    queries = []

    for _ in range(q):
        queries.append(list(map(int, input().rstrip().split())))

    result = dynamicArray(n, queries)
    fptr.write('\n'.join(map(str, result)))
    fptr.write('\n')

    fptr.close()
    • raghuchahar007 + 0 comments
      [deleted]
    • nikhilsai_v + 0 comments

      it works only for two sequences if there are more than 2 sequences then error