Challenge cum problem in C/C++

Replies

• 

  Prasad Ajinkya

  heres a hint - spiral
• 

  RajdeepCE

  I know it is spiral, but how to implement it in program?
• 

  slashfear

  Hi Rajdeep,
  
  Nice question dude!!!! 😁
  
  But I am wondering......😕 if this is your home work or what......?
  
  Any ways I know the solution buddy.......;-) it is also called as The Spiral Matrix
  
  So this is how you implement in C++ (as well as in C 😛)
  
  

  
  [B]/* Written by: Arvind(slashfear)
     Language: C++     */
  
  
  #include 
  
  using namespace std;
  
  void SpiralIni(int **A, int N)
  {
    int i = 0, j = 0;
    int x0 = 0, x1 = N, y0 = 0, y1 = N;
    int m = 0;
    bool up = true;
  
    while(1)
    {
      if(up)
      {
        for (j; j < y1; ++ j) A[i][j] = ++ m;
  
        -- j; ++ i; -- y1;
  
        for (i; i < x1; ++ i) A[i][j] = ++ m;
  
        -- i; -- j; -- x1;
  
        up = false;
      } else
      {
        for (j; j >= y0; -- j) A[i][j] = ++ m;
  
        ++ j; -- i; ++ y0;
  
        for (i; i >= x0+1; -- i) A[i][j] = ++ m;
  
        ++ i; ++ j; ++ x0;
  
        up = true;
      }
  
      if (m+1 > N*N) break;
    }
  }
  
  int main()
  {
    int N;
    cout<<"Enter the value of N : ";
    cin>> N;
    int **a = new int* [N];
    for (int i = 0; i < N; ++ i) a[i] = new int [N];
  
    SpiralIni(a,N);
  
    for( int i = 0; i < N; ++ i)
    {
      for(int j=0; j < N; ++ j) cout<<"\t"<< a[i][j];
  
      cout<<"\n";
    }
  
    for (int i = 0; i < N; ++i) delete []a[i];
    delete []a;
  return 0;
  }[/B]
  

  
  
  Output:
  

  [B]Enter the value of N: 5
  
  1   2   3   4   5
  16  17  18  19  6
  15  24  25  20  7
  14  23  22  21  8
  13  12  11  10  9[/B]
  

  
  Mission accomplished ;-)
  
  -Arvind(slashfear)
• 

  RajdeepCE

  You are really rocking slashfear. This problem was asked in coding challenge last year in our college, but I didnt go through it. Than I suddnely remember it & I posted it here. And now I found the solution thanks to you. I want to learn lots of stuff from you. You are great!!!!
• 

  slashfear

  Hi Rajdeep,
  
  
  No probs buddy....... knowledge is to share no need thanks and all dude😁
  
  
  
  
  
  
  -Arvind(slashfear);-)
• 

  pradeep_agrawal

  That's cool, the program work perfectly as required. Slashfear, you rock buddy.
  
  Here is my piece of code for same problem.
  
  

  #include "stdio.h"
  
  
  void create_spiral(int **spiral, int spiral_size, int spiral_level) {
    int i = 0;
  
    //Calculating first value at level spiral_level
    int current_size = spiral_size - 2*spiral_level;
    int value = spiral_size*spiral_size - current_size*current_size + 1;
  
    //Populate data from left to right for spiral at level spiral_level
    for(i = 0; i < (spiral_size - 2*spiral_level); i++) {
      spiral[spiral_level][spiral_level+i] = value;
      value++;
    }
  
    //Populate data from top to bottom for spiral at level spiral_level
    for(i = 1; i < (spiral_size - 2*spiral_level); i++) {
      spiral[spiral_level + i][spiral_size - spiral_level - 1] = value;
      value++;
    }
  
    //Populate data from right to left for spiral at level spiral_level
    for(i = (spiral_size - 2*spiral_level -2); i >= 0; i--) {
      spiral[spiral_size - spiral_level -1][spiral_level + i] = value;
      value++;
    }
  
    //Populate data from bottom to top for spiral at level spiral_level
    for(i = (spiral_size - 2*spiral_level -2); i > 0; i--) {
      spiral[spiral_level + i][spiral_level] = value;
      value++;
    }
  }
  
  
  void print_spiral(int **spiral, int spiral_size) {
    int i = 0, j = 0;
  
    for(i = 0; i < spiral_size; i++) {
      for(j = 0; j < spiral_size; j++) {
        printf("%d ", spiral[i][j]);
      }
      printf("\n");
    }
  }
  
  
  int main() {
    int spiral_size = 0;
    int **spiral = NULL;
    int max_spiral_level = 0;
    int i = 0;
  
    //Take size of spiral as input
    scanf("%d", &spiral_size);
  
    //validate size of spiral
    if(spiral_size < 1) {
      printf("Invalid size for spiral\n");
      return 0;
    }
  
    //Allocate memory for spiral
    spiral = (int**)malloc(sizeof(int*) * spiral_size);
    for(i = 0; i < spiral_size; i++) {
      spiral[i] = (int*)malloc(sizeof(int) * spiral_size);
    }
  
    //Determine number of level of spiral
    max_spiral_level = (spiral_size + 1)/2;
  
    //For each level of spiral populate data
    for(i = 0; i < max_spiral_level; i++) {
      create_spiral(spiral, spiral_size, i);
    }
  
    //Print the spiral
    print_spiral(spiral, spiral_size);
  
    //Free memory allocated for spiral
    for(i = 0; i < spiral_size; i++) {
      free(spiral[i]);
    }
    free(spiral);
  
    return 0;
  }
  

  Compile the file with above code and run as:
  a.exe < input.txt > output.txt [on windows]
  a.out < input.txt > output.txt [on linux]
  
  Here,
  a.exe or a.out are the executables generated after compilation
  
  input.txt is the file containing order of the spiral matrix need to be given as input, e.g., if the matrix is of order 5, then input.txt will be
  5
  
  output.txt is the output file containing result, for given example output.txt will contain
  1 2 3 4 5
  16 17 18 19 6
  15 24 25 20 7
  14 23 22 21 8
  13 12 11 10 9
  
  -Pradeep