C-一维数组组中的最大值

Question

So, my task is to let user fill one dimensional array A. This array has M number of groups and P members in each group. I need to fill array B with maximum values of each group in A array and display results of maximum values in each group after. I couldn't figure out any way to do it. I would really appreciate your help since I am a beginner programmer and doing my best to study. So my main problem in code is fillBArray function.

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

int checkingvariable(int k, int a, int b);
void fillArray(int M, int P,int A[]);
void printArray(int M, int P,int A[]);
void fillBArray(int M, int P,int A[]);


int main()
{

int M, P;

    printf("Enter M (the number of groups): ");
    scanf("%d", &M);

    M=checkingvariable(M, 1, 10);

    printf("Enter P (the number of cars in one group): ");
    scanf("%d", &P);

    P=checkingvariable(P, 1, 10);
    int i = P*M;
    int A[i];
    fillArray(M, P, A);
    printArray(M, P, A);
    fillBArray(M, P, A);
    return 0;
}

void printArray(int M, int P,int A[])
    {
        int i;
        for (i=0 ; i< M*P ; i++)
        {
              printf("%d ", A[i]);
              printf("\n");
        }
    }

void fillArray(int M, int P, int A[])
    {

        int i;
        for (i=0 ; i< M*P ; i++)
        {
             printf("Enter speed of car %d: ", i+1);
             scanf("%d", &A[i]);
        }

    }

void fillBArray(int M, int P, int A[])
{
    int c, k=0;
    int maximum = A[0];
    int B[M], group;
    for (c = 0; c < P*M; c++)
    {
        if (A[c] > maximum)
        {
            maximum  = A[c];
        }
        maximum = B[k];
        printf("Maximum value for %d group is: %d", group, maximum);
    }
}

int checkingvariable(int k, int a, int b)
    {
        if (k<a || k>b)
            {
                while(k<a || k>b)
                    {
                        printf("Enter correct value between %d and %d: ", a, b);
                        scanf("%d", &k);
                    }
            }
            return k;
    }

Answer 1

One way is to replace one loop with two nested loops. The outer loop would iterate groups, while the nested loop would iterate members in each group.

One observation before you begin: members of a group g in the array A are located between indexes g*P , inclusive, and (g+1)*P , exclusive. Member m of a group is located at the index A[g*P + m] .

Now it should be clear how to make your loops:

for (int g = 0 ; g != M ; g++) { // Groups
    int max = A[g*P];
    for (int m = 1 ; m != P ; m++) { // Members
        ... // Compute max
    }
    // Store max for group g in B[]
}

Answer 2

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

int checkingvariable(int k, int a, int b);
void fillArray(int M, int P,int A[]);
void printArray(int M, int P,int A[]);
void fillBArray(int M, int P,int A[]);


int main()
{

int M, P;

    printf("Enter M (the number of groups): ");
    scanf("%d", &M);

    M=checkingvariable(M, 1, 10);

    printf("Enter P (the number of cars in one group): ");
    scanf("%d", &P);

    P=checkingvariable(P, 1, 10);
    int i = P*M;
    int A[i];
    fillArray(M, P, A);
    printArray(M, P, A);
    fillBArray(M, P, A);
    return 0;
}

void printArray(int M, int P,int A[])
    {
        int i;
        for (i=0 ; i< M*P ; i++)
        {
              printf("%d ", A[i]);
              printf("\n");
        }
    }

void fillArray(int M, int P, int A[])
    {

        int i;
        for (i=0 ; i< M*P ; i++)
        {
             printf("Enter speed of car %d: ", i+1);
             scanf("%d", &A[i]);
        }

    }

/*void fillBArray(int M, int P, int A[])
{
    int c, k=0;
    int maximum = A[0];
    int B[M], group;
    for (c = 0; c < P; c++)
    {
        if (A[c] > maximum)
        {
            maximum  = A[c];
        }
        if (c < P)
        {
            group = 1;
            maximum = A[c];
            printf("Maximum value for %d group is: %d", group, maximum);
        }
        if (c < P*2)
        {
            group = 2;
            k=1;
            maximum = A[c];
            printf("Maximum value for %d group is: %d", group, maximum);
        }
    }
}*/

void fillBArray(int M, int P, int A[])
{
    int B[M], maximum = 0, m;
    for (int g = 0 ; g != M ; g++)// Groups
    {
        int max = A[g*P];
        for (m = 0 ; m != P ; m++) // Members
        {
            if (A[g*P + m] > maximum)
            {
                maximum = A[g*P + m];
            }
        }
    B[g] = maximum;
    printf("Maximum value for %d group is: %d", g+1, maximum);
    printf("\n");
    maximum = 0;
    }
}

int checkingvariable(int k, int a, int b)
    {
        if (k<a || k>b)
            {
                while(k<a || k>b)
                    {
                        printf("Enter correct value between %d and %d: ", a, b);
                        scanf("%d", &k);
                    }
            }
            return k;
    }

This is answer to my problem, check fillBArray.