Having problems in using linked lists

[kishore84]

#include<stdio.h>
#include <stdlib.h>
#include <time.h>
#include<conio.h>

const int LOW = 1;
const int HIGH = 150;
int main()
{                   
  int grid[30][30]={0},x,j,i,die;
  int data_points, tempx, tempy;
  for(x=0;x<150;x++)
  {
    tempx = rand() % 30 + 1;
    tempy = rand() % 30 + 1;
    data_points = rand() % (HIGH - LOW + 1) + LOW;
    grid[tempx][tempy]=data_points;
    printf("%d\n",data_points);
  }
  for(i=0;i<30;i++){
    for(j=0;j<30;j++){
      printf("x=%d\t y=%d\t index=%d\n",i,j,grid[i][j]);
  }}
  getch();
}

when we run this program we get the value for the grid[j].In this as we are generating the values randomly by the rand function.So we may get more than one value at some point in the grid[j] but the values are getting overwritten.Can anyone help in implementing linked lists to this concept and trying to get more values for the grid[j].

Hoping a positive reply

[monkey_king]

I don't really understand what your doing here,
this has nothing to do with linked lists.

you need to do use a struct like

typedef struct lnode
{
int data;
struct lnode *next;
} listnode_t;

[William Hemsworth]

Why have you made two threads posting the exact same (badly presented) question.. its not going to make it get answered any quicker.

[ArkM]

1. Please, use code tag for your snippet:
[code=c] your snippet here

[/code]
2. Serious (and classic) mistake:

int grid[30][30]={0},x,j,i,die;
...
tempx = rand() % 30 + 1; /* in 1..30 range */
tempy = rand() % 30 + 1;
...
grid[tempx][tempy]=data_points; /* must be in 0..29 range */

3.

Can anyone help in implementing linked lists to this concept

Linked list of what? You have a grid of integers. Do you want a grid of lists of integers?!
What for? Why randomize i and j? Assign randomized values to EVERY cell of the grid - that's the grid randomization - exactly the same in probability theory sense as overrandomizing with random (i,j,value). If you want to study "random hits with random weights", present more exact specifications.

[ArkM]

Alas, I put my foot into this double trap...

[kishore84]

1. Please, use code tag for your snippet:
[code=c] your snippet here

[/code]
2. Serious (and classic) mistake:

int grid[30][30]={0},x,j,i,die;
...
tempx = rand() % 30 + 1; /* in 1..30 range */
tempy = rand() % 30 + 1;
...
grid[tempx][tempy]=data_points; /* must be in 0..29 range */

3.
Linked list of what? You have a grid of integers. Do you want a grid of lists of integers?!
What for? Why randomize i and j? Assign randomized values to EVERY cell of the grid - that's the grid randomization - exactly the same in probability theory sense as overrandomizing with random (i,j,value). If you want to study "random hits with random weights", present more exact specifications.

what i need here is to create a linked list of integers i.e data_points in this case.I need to keep all the data_points in the grid[30[30] and and print out the values for a given position in the grid .
As we are generating the data_points randomly there will be 2 or more values for a certain position as both the x,y coordinates are also generated randomly.So, that is why i need to create a list for the data_points to print out all the values.

So, finally i need to print out the x,y coordinates and their respective data_values for a given position(i.e x=24 y=12 index=23,88,56) if there are 3 indexes that have come randomly for a certain position in the grid.

[ArkM]

I don't like a chimera of a matrix and a list of integers. Better use jagged array concept.

Regrettably, it's my time to go. If this thread will be opened tomorrow (may be ;)) I should try to help you with jagged array implementation.

PS. Of course, the simplest solution is 3D array: grid + data_points values dimension. Add a matrix with current sizes for every grid cell - that's all. Memory in exchange for speed and simplicity...

[ArkM]

Look at this dynamic grid improvisation:
Header file hitstuff:

/** @file
 *  MxN dynamic grid declarations.
 *  No warranties, no maintenance.
 */
#ifndef HITSTUFF_H
#define HITSTUFF_H
/** Initialize MxN grid module */
void hitInit(int m, int n);
/** Deallocate grid module resourses */
void hitStop();
/** Returns a number of grid rows */
int hitRows();
/** Returns a number of grid columns */
int hitCols();
/** Returns total hits counter */
int hitCounter();
/** Misc: set dyn memory increment in num of elements */
int hitStep(int step);
/** Add the next value to grid[i][j] */
void hitNext(int i, int j, int value);
/** Returns a number of hits in grid[i][j] */
int hitSize(int i, int j);
/** Returns the pointer to grid[i][j] data */
int* hitData(int i, int j);
/** Allocate 3d array for grid[i][j][k] values.
 *  Don't forget to free(this pointer).
 */
int*** hit3D();
#endif

Implementation file hitstuff.c:

/** @file
 *  Dynamic MxN grid module in C 
 *  (C++ class object surrogate).
 *  Compiled and tested in C and C++.
 */
#include "hitstuff.h"
/* Dependencies:
#include <stdlib.h>
 */
/** Grid module implementation macros */
#define IJ(i,j)  ((i)*N+(j))
#define PTR(i,j) (hitSlot+IJ(i,j))
/** Grid internal container element type */
typedef
struct Hitstr {
    int*data;
    int size;
    int curr;
} Hits;
/** Locals */
static int M, N, hitCnt;
static size_t addStep  = 8;
/** Non-initialized cell internal value */
static Hits   dummy[1] = {{&dummy[0].size,0,0}};
/** Pointer to allocated grid container */
static Hits*  hitSlot  = dummy;

/** Internal: reinitialize dummy cell */
static void hitMisc() {
    Hits* p = dummy;
    if (p->data != &p->size) {
        p->data = &p->size;
        p->curr = p->size = 0;
    }
}
/** Functional interface implementation */
int hitRows() { return M; }
int hitCols() { return N; }

int hitCounter() { return hitCnt; }

int hitStep(int step)
{
    int old = addStep;
    if (step > 0)
        addStep = step;
    return old;
}

void hitNext(int i, int j, int value)
{
    Hits* p = PTR(i,j);
    if (p->curr >= p->size) {
        p->data = p->size
        ? (int*)realloc(p->data,
                sizeof(int)*(p->size += addStep))
        : (int*)malloc(sizeof(int)*(p->size = addStep));
    }
    p->data[p->curr++] = value;
    ++hitCnt;
}

void hitStop()
{
    if (hitCnt) {
        int i, mn = M * N;
        Hits* p = hitSlot;
        for (i = 0; i < mn; ++i, ++p)
            if (p->curr)
                free(p->data);
        hitMisc();
    }
    if (hitSlot) {
        free(hitSlot);
        hitSlot = dummy;
    }
    M = N = hitCnt = 0;
}

void hitInit(int m, int n)
{
    int i, mn = m * n;
    Hits* p;

    if (hitSlot != dummy)
        hitStop();
    M = m;
    N = n;
    hitSlot = (Hits*)malloc(sizeof(*hitSlot)*mn);
    for (i = 0, p = hitSlot; i < mn; ++i, ++p) {
        p->curr = p->size = 0;
        p->data = &p->size;
    }
    hitCnt = 0;
}

int hitSize(int i, int j)
{
    return PTR(i,j)->curr;
}

int* hitData(int i, int j)
{
    return PTR(i,j)->data;
}

int*** hit3D()
{
    void** ppvoid;
    void** p;
    void** q;
    int i, j, m, n;
    
    if (hitSlot == dummy)
        m = n = 1;
    else
        m = M, n = N;

    ppvoid = p = (void**)malloc(sizeof(*ppvoid)*m*(n+1));
    for (i = 0; i < M; ++i)
    {
        ppvoid[i] = q = (p += M);
        for (j = 0; j < N; ++j)
            q[j] = hitData(i,j);
    }
    return (int***)ppvoid;
}

Test routine (grid 3x3, 9 values for every cell except diagonally uninitialized):

#include "hitstuff.h"

void TestGrid()
{
    int i, j, k;
    int*** grid;

    hitInit(3,3);
    /* Initialize grid */
    for (i = 0; i < hitRows(); ++i)
    {
        for (j = 0; j < hitCols(); ++j)
        {
            if (i != j)
            for (k = 0; k < 9; ++k)
                hitNext(i,j,(i+1)*100+(j+1)*10+k+1);
            /* ijk values for clearness */
        }
    }
    /* Make 3D jagged array with all accumulated values */
    grid = hit3D(); 
    /* Print all values */
    for (i = 0; i < hitRows(); ++i)
    {
        for (j = 0; j < hitCols(); ++j)
        {
            printf("[%d][%d]:",i+1,j+1);
            if (hitSize(i,j))
            {
                for (k = 0; k < hitSize(i,j); ++k)
                    printf(" %d",grid[i][j][k]);
            }
            else printf(" None");
            putchar('\n');
        }
    }
    /* Print number of values in the grid */
    for (i = 0; i < hitRows(); ++i)
    {
        for (j = 0; j < hitCols(); ++j)
        {
            printf(" %d",hitSize(i,j));
        }
        putchar('\n');
    }
    free(grid);
    hitStop();
}
/* Output:
[1][1]: None
[1][2]: 121 122 123 124 125 126 127 128 129
[1][3]: 131 132 133 134 135 136 137 138 139
[2][1]: 211 212 213 214 215 216 217 218 219
[2][2]: None
[2][3]: 231 232 233 234 235 236 237 238 239
[3][1]: 311 312 313 314 315 316 317 318 319
[3][2]: 321 322 323 324 325 326 327 328 329
[3][3]: None
 0 9 9
 9 0 9
 9 9 0
*/

Minimal debugging only.
You may use this code for any (non-commercial;)) purposes...