CodinGame n°2 (32min 17s)

// Read inputs from stdin. Write outputs to stdout.

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

typedef struct
{
    int v;
    int i;
} Couple;

static int n;
static int *v;
static Couple *cp;

int compare(const void *a, const void *b)
{
    return (((Couple*)b)->v - ((Couple*)a)->v);
}

void init()
{
    int i;

    scanf("%d\n", &n);

    v = malloc(n * sizeof(int));

    for (i=0; i<n; i++)
        scanf("%d", v+i);

    cp = malloc(n * sizeof(Couple));

    for (i=0; i<n; i++)
    {
        cp[i].v = v[i];
        cp[i].i = i;
    }

    qsort(cp, n, sizeof(Couple), compare);
}

int result()
{
    int i, j;
    int loss = 0;

    for (i=0; i<n; i++)
    {
        for (j=n-1; cp[j].v<cp[i].v; j--)
        {
            if (cp[j].i > cp[i].i)
            {
                if (cp[j].v-cp[i].v < loss)
                    loss = cp[j].v-cp[i].v;

                break;
            }
        }
    }

    return loss;
}

int main()
{
    init();

    printf("%d", result());

    return 0;
}