2D Array

https://www.hackerrank.com/challenges/2d-array/problem

모래 시계에 관한 문제로, 문제가 엄청 복잡한 것처럼 설명이 되어있지만

그냥 단순하게 이차원 배열에서 원소들의 합 중 가장 큰 값을 찾는 문제이다.

 

#include <assert.h>
#include <limits.h>
#include <math.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char* readline();
char** split_string(char*);

// Complete the hourglassSum function below.
int hourglassSum(int arr_rows, int arr_columns, int** arr) {
    int temp=-9999, h=0;
    for(int i=0; i<arr_rows/2+1;i++){
        for(int j=0; j<arr_columns/2+1; j++){
            h=arr[i][j]+arr[i][j+1]+arr[i][j+2]+arr[i+1][j+1]+arr[i+2][j]+arr[i+2][j+1]+arr[i+2][j+2];
            if(temp<h)  temp=h;
        }
    }
    return temp;

}

int main()
{
    FILE* fptr = fopen(getenv("OUTPUT_PATH"), "w");

    int** arr = malloc(6 * sizeof(int*));

    for (int i = 0; i < 6; i++) {
        *(arr + i) = malloc(6 * (sizeof(int)));

        char** arr_item_temp = split_string(readline());

        for (int j = 0; j < 6; j++) {
            char* arr_item_endptr;
            char* arr_item_str = *(arr_item_temp + j);
            int arr_item = strtol(arr_item_str, &arr_item_endptr, 10);

            if (arr_item_endptr == arr_item_str || *arr_item_endptr != '\0') { exit(EXIT_FAILURE); }

            *(*(arr + i) + j) = arr_item;
        }
    }

    int arr_rows = 6;
    int arr_columns = 6;

    int result = hourglassSum(arr_rows, arr_columns, arr);

    fprintf(fptr, "%d\n", result);

    fclose(fptr);

    return 0;
}

char* readline() {
    size_t alloc_length = 1024;
    size_t data_length = 0;
    char* data = malloc(alloc_length);

    while (true) {
        char* cursor = data + data_length;
        char* line = fgets(cursor, alloc_length - data_length, stdin);

        if (!line) { break; }

        data_length += strlen(cursor);

        if (data_length < alloc_length - 1 || data[data_length - 1] == '\n') { break; }

        size_t new_length = alloc_length << 1;
        data = realloc(data, new_length);

        if (!data) { break; }

        alloc_length = new_length;
    }

    if (data[data_length - 1] == '\n') {
        data[data_length - 1] = '\0';
    }

    data = realloc(data, data_length);

    return data;
}

char** split_string(char* str) {
    char** splits = NULL;
    char* token = strtok(str, " ");

    int spaces = 0;

    while (token) {
        splits = realloc(splits, sizeof(char*) * ++spaces);
        if (!splits) {
            return splits;
        }

        splits[spaces - 1] = token;

        token = strtok(NULL, " ");
    }

    return splits;
}