LeetCode #59 Spiral Matrix II

/*
* Abstract: Exactly the same idea as #54
*/
#define DIR_RIGHT 0
#define DIR_DOWN 1
#define DIR_LEFT 2
#define DIR_UP 3
void next(int *i, int *j, int *dir, int *right_barr, int *bottom_barr, int *left_barr, int *top_barr) {
    if (*dir == DIR_RIGHT) {
        if (*j == *right_barr) {
            (*right_barr)--;
            (*i)++;
            *dir = DIR_DOWN;
        } else {
            (*j)++;
        }
    } else if (*dir == DIR_DOWN) {
        if (*i == *bottom_barr) {
            (*bottom_barr)--;
            (*j)--;
            *dir = DIR_LEFT;
        } else {
            (*i)++;
        }
    } else if (*dir == DIR_LEFT) {
        if (*j == *left_barr) {
            (*left_barr)++;
            (*i)--;
            *dir = DIR_UP;
        } else {
            (*j)--;
        }
    } else if (*dir == DIR_UP) {
        if (*i == (*top_barr)) {
            (*top_barr)++;
            (*j)++;
            *dir = DIR_RIGHT;
        } else {
            (*i)--;
        }
    }
}

int** generateMatrix(int n, int* returnSize, int** returnColumnSizes){
    int **matrix = (int**)malloc(n * sizeof(*matrix));
    *returnColumnSizes = (int*)malloc(n * sizeof(int));
    for (int i = 0; i < n; i++) { 
        matrix[i] = (int*)malloc(n * sizeof(int)); 
        (*returnColumnSizes)[i] = n;
    }
    *returnSize = n;
    
    int right_barr = n - 1, bottom_barr = n - 1, left_barr = 0, top_barr = 1;
    int i = 0, j = 0, dir = 0, val = 0, totalSize = n * n;
    while (val < totalSize) {
        val++;
        matrix[i][j] = val;
        next(&i, &j, &dir, &right_barr, &bottom_barr, &left_barr, &top_barr);
    }
    
    return matrix;
}