Memory allocation problem, with large values

Question

Well I’m in trouble on one issue

Enunciation

Given an integer vector, your task is to find the k-th occurrence (left to right) of an integer v in the vector. To make the problem more difficult (and more interesting!), you should answer m queries of this type.

Input of the test cases

8 4
1 3 2 2 4 3 2 1
1 3
2 4
3 2
4 2

In this case 1.3 I am looking for the number 3, in its first occurrence in my vector, so I use the number as Indice, the result and 2, as my code does

Logic I used in the question

to solve this problem I used the following logic, I created the element struct that will receive the value and the Indice, then I created the Map struct in it will have an element struct matrix, and an array of size that will have the size of the Indice of my struct, so when I call the function creates() I use the calloc that Zera my vector, in the insert function, I check if the Indice I’m entering and 0, why if it means there are no elements in that Indice, and fill the data normally, when it is in Else, I use realloc, to add the element, in my matrix.

My code

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

typedef struct elemento
{
    int valor, chave;
} Elemento;

typedef struct map
{
    Elemento **dados;
    int *tamanho;
} Map;

Map *cria(int tam);
int insere(Map *mp, int valor, int i);
Map *libera(Map *mp, int tam);

int main(int argc, char** argv)
{
    int tam, teste;
    int numero, indice;
    int i;
    while(scanf("%d %d", &tam, &teste) != EOF)
    {
        Map *matriz = cria(tam);
        for(i = 0; i < tam; i++)
        {
            scanf("%d", &numero);
            insere(matriz, numero, i + 1);
        }
        for(i = 0; i < teste; i++)
        {
            scanf("%d %d", &indice, &numero);
            if(indice <= matriz->tamanho[numero])
            {
                printf("%d\n", matriz->dados[numero][indice - 1].chave);
            }
            else
            {
                printf("0");
            }
        }
        matriz = libera(matriz, tam);
    }

    return 0;
}

Map *cria(int tam)
{
    Map *mp = malloc(sizeof(Map));
    if(!mp) return NULL;
    mp->tamanho = calloc(tam, sizeof(int));
    mp->dados = malloc(sizeof(Elemento*) * tam);
    return mp;
}

int insere(Map *mp, int valor, int i)
{
    if(mp->tamanho[valor] == 0)
    {
        mp->dados[valor] = malloc(sizeof(Elemento));
        mp->dados[valor][0].valor = valor;
        mp->dados[valor][0].chave = i;
        mp->tamanho[valor]++;
    }
    else
    {
        int size = mp->tamanho[valor];
        mp->dados[valor] = realloc(mp->dados[valor], (size + 1) * sizeof(Elemento));
        mp->dados[valor][size].valor = valor;
        mp->dados[valor][size].chave = i;
        mp->tamanho[valor]++;
    }
    return 1;
}

Map *libera(Map *mp, int tam)
{
    int i;
    for(i = 0; i < tam; i++)
    {
        free(mp->dados[i]);
    }
    free(mp);
    return NULL;
}

Answer 1

From what I understand of the problem, and guiding me by the principle KISS, I would do:

#include <stdio.h>
#include <stdlib.h>
int main() {
    int tam, casos, ocor, num, *vet, i, j, k, l;
    scanf("%d %d", &tam, &casos);
    vet = malloc(tam * sizeof(int));
    if (vet == NULL)
        exit(1);
    for (i=0; i<tam; i++)
        scanf("%d", &vet[i]);
    for (j=0; j<casos; j++) {
        scanf("%d %d", &ocor, &num);
        k = 0;
        for (l=0; l<tam && k<ocor; l++)
            if (vet[l] == num)
                k++;
        if (k == ocor)
            printf("A %dª ocorrência de %d encontra-se na posição %d\n", ocor, num, l);
        else
            printf("Não existem %d ocorrências de %d no vetor\n", ocor, num);
    }
    free(vet);
    return 0;
}