/*
Challenge 200

Task 1: Arithmetic Slices
Submitted by: Mohammad S Anwar
You are given an array of integers.

Write a script to find out all Arithmetic Slices for the given array of integers.

An integer array is called arithmetic if it has at least 3 elements and the
differences between any three consecutive elements are the same.


Example 1
Input: @array = (1,2,3,4)
Output: (1,2,3), (2,3,4), (1,2,3,4)
Example 2
Input: @array = (2)
Output: () as no slice found.
*/

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

void* check_mem(void* p) {
    if (!p) {
        fputs("Out of memory", stderr);
        exit(EXIT_FAILURE);
    }
    return p;
}

bool is_arithmetic(int nums[], int nums_size) {
    if (nums_size < 3)
        return false;
    int step = nums[1] - nums[0];
    for (int i = 2; i < nums_size; i++) {
        if (nums[i] - nums[i-1] != step)
            return false;
    }
    return true;
}

void print_slices(int nums[], int nums_size) {
    const char* sep = "";

    printf("(");
    for (int i = 0; i < nums_size-2; i++) {
        for (int j = i+2; j < nums_size; j++) {
            if (is_arithmetic(nums+i, j-i+1)) {
                printf("%s", sep);
                sep = "), (";
                for (int k = i; k <= j; k++) {
                    printf("%d", nums[k]);
                    if (k != j)
                        printf(",");
                }
            }
        }
    }
    printf(")\n");
}

int main(int argc, char* argv[]) {
    argv++; argc--;
    if (argc == 0) {
        fputs("usage: ch-1 nums...", stderr);
        exit(EXIT_FAILURE);
    }

    int* nums = check_mem(malloc(argc*sizeof(int)));
    for (int i = 0; i < argc; i++)
        nums[i] = atoi(argv[i]);
    print_slices(nums, argc);

    free(nums);
}