Why this program to sort array doesnt work?-CodePudding

Im trying to learn C and I'm doing this program to sort an array but It doesn't work and I'm not sure why, I tested each function and works well, someone knows if its a problem of variables or something?

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

#define N 5

int V[5] = { -383, 386, 277, 415, 293 };

void displayArray(int arr[], int size)
{
    int i;
    for (i = 0; i < size; i  )
        printf("%d ", arr[i]);
}

int maxim(int v[], int n)
{
    int i, m;
    m = v[0];
    /*
    Find maxim element
    */
    for (i = 1; i < n; i  )
        if (v[i] > m)
            m = v[i];
    /*
    Search element position
    */
    for (i = 0; i < N; i  )
        if (v[i] == m)
            return i;
}

void sort(int v[], int n)
{
    int i, pos, t;
    for (i = 0; i < n; i  )
        pos = maxim(v, n - i);

    /*
  Swap elements
  */
    t = v[n - 1 - i];
    v[n - 1 - i] = v[pos];
    v[pos] = t;
}

int main()
{
    displayArray(V, N);
    sort(V, N);
    printf("\n");
    displayArray(V, N);
    return 0;
}

The output is

-383 386 277 415 293 - Original Array

21900 386 277 415 293 - 'Sorted' Array

CodePudding user response：

First fix your maxim function. Its purpose is to find the maximum index of a sequence v of magnitude n. Therefore, remembering the maximum value in m is irrelevant; you want to remember where it resides :

int maxim(int v[], int n)
{
    int m=0;
    for (int i=1; i<n;   i)
    {
        if (v[m] < v[i])
            m = i; // save new max location
    }
    return m;
}

After that, the sort, which is completely wrong. This:

int i, pos, t;
for (i = 0; i < n; i  )
    pos = maxim(v, n - i);

is pointless. It calculates, and overwrites, pos repeatedly until the last iteration, which is the only one that is processed with:

t = v[n - 1 - i];
v[n - 1 - i] = v[pos];
v[pos] = t;

E..g, you sort one element, and then exit your sort. You need to sort them all, starting with the full segment, then reducing the size of the segment by one with each iteration after you swap the most-maximum element into position for that segment.

void sort(int v[], int n)
{
    for (int i=0; i<(n-1);   i)
    {
        int m = maxim(v, (n-i)); // max of this segment
        int tmp = v[m];
        v[m] = v[n-i-1];
        v[n-i-1] = tmp;
    }
}

CodePudding user response：

pos = maxim(v, n - i);

should be

pos = maxim(v, n);