#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <math.h>
#include <malloc.h>

typedef int32_t s32;

struct vec2
{
    s32 x;
    s32 y;
};

vec2 dirTable[] = { { 1, 0 }, { 0, -1 }, { -1, 0 }, { 0, 1 } };
vec2 neighborTable[] = { { 0, 1 }, { 0, -1 }, { 1, -1 }, { 1, 0 }, { 1, 1 }, { -1, -1 }, { -1, 0 }, { -1, 1 } };

s32 SumNeighbors(s32 *grid, vec2 pos);

int main(int argc, char **argv)
{
    // Guess
    s32 *grid = (s32 *)calloc(1024 * 1024, sizeof(s32));

    s32 largest = 0;
    s32 goal = 277678;

    vec2 pos = { 511, 511 };
    s32 dir = 0;

    s32 stepIter = 0;
    s32 stepMax = 1;
    s32 spiralStep = 0;       // 0,1 0,1 ...

    // Fill first square
    grid[(1024 * pos.y) + pos.x] = 1;

    for (s32 i = 1; i < goal; i++)
    {
        pos.x += dirTable[dir].x;
        pos.y += dirTable[dir].y;

        s32 acc = grid[(1024 * pos.y) + pos.x];

        stepIter++;
        if (stepIter == stepMax)
        {
            stepIter = 0;

            dir++;
            if (dir > 3)
            {
                dir = 0;
            }

            spiralStep++;
            if (spiralStep == 2)
            {
                spiralStep = 0;

                stepMax++;
            }
        }
    }

    free(grid);

    printf("Largest: %d\n", largest);

    system("pause");

    return 0;
}

s32 SumNeighbors(s32 *grid, vec2 pos)
{
    s32 result = 0;

    vec2 n = {};
    for (s32 ni = 0; ni < 8; ni++)
    {
        n = neighborTable[ni];
        result += grid[(1024 * (pos.y + n.y)) + (pos.x + n.y)];
    }

    return result;
}