pureC4

#include <stdio.h>

// Отладка

int array[] = {1, 2, 3, 4, 5, 3, 2, -5};

int less(unsigned long i, unsigned long j)
{
    return array[i] < array[j];
}

unsigned long peak(unsigned long, int (*)(unsigned long, unsigned long));

int main()
{
    unsigned long i = peak(8, less);
    if ((i == 0 || array[i] >= array[i - 1]) && (i == 7 || array[i] >= array[i + 1])) {
        printf("CORRECT\n");
    } else {
        printf("WRONG\n");
    }
    return 0;
}

// Решение

unsigned long peak(unsigned long nel, int (*less)(unsigned long, unsigned long))
{
    if (!less(0, 1)) {
        return 0;
    } else if (!less(nel - 1, nel - 2)) {
        return nel - 1;
    }

    for (unsigned long i = 1; i < nel - 1; i++) {
        if (!less(i, i - 1) && !less(i, i + 1))
            return i;
    }
}