sistemas lineares-triangularização com troca de linhas

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

/* run this program using the console pauser or add your own getch, system("pause") or input loop */


int main() {
    int n;
    printf("digite o numero de equacoes: ");
    scanf("%d", &n);
    int a[n][n], i, j, k, b[4], aux[n], o, s, x=0;
    int m;
    for ( i=0; i<n; i++ ){
        for ( j=0; j<n; j++ )
        {
          printf (" [%d][%d] = ", i, j);
          scanf ("%d", &a[i][j]);
        }
        printf("\n");
    }
    for(k=0;k<n;k++){
        for(i=k+1;i<n;i++){
            while((a[k][k])==0){
                for(o=0;o<n;o++){
                    aux[o]=a[o][k];
                }
                for(o=0;o<n;o++){
                    a[o][k]=a[o][k+1];
                }
                for(o=0;o<n;o++){
                    a[o][k+1]=aux[o];
                }
            }
            m=a[i][k]/a[k][k];
            for(j=k;j<n;j++){
                   a[i][j]=a[i][j]-m*a[k][j];
            }
            a[i][k]=0;
            b[i]=b[i]-m*b[k];
        }


    }
    for ( i=0; i<n; i++ ){
        for ( j=0; j<n; j++ )
        {
          printf ("%d ", a[i][j]);
        }
        printf("\n");
    }
    return 0;
}