// SQL Solution (Brute Force)
char* sqlQuery = 
"SELECT DISTINCT p.product_id, p.product_name\n"
"FROM Product p\n"
"WHERE p.product_id IN (\n"
"    SELECT DISTINCT s1.product_id \n"
"    FROM Sales s1 \n"
"    WHERE s1.sale_date >= '2019-01-01' \n"
"    AND s1.sale_date <= '2019-03-31'\n"
")\n"
"AND p.product_id NOT IN (\n"
"    SELECT DISTINCT s2.product_id \n"
"    FROM Sales s2 \n"
"    WHERE s2.sale_date < '2019-01-01' \n"
"    OR s2.sale_date > '2019-03-31'\n"
");";

// C implementation
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct {
    int product_id;
    char product_name[100];
} Product;

typedef struct {
    int product_id;
    char sale_date[11];
} Sale;

typedef struct {
    int product_id;
    char product_name[100];
} Result;

Result* bruteForceSolution(Product* products, int productCount, 
                          Sale* sales, int saleCount, int* resultSize) {
    // Arrays to track products
    int q1Products[1000] = {0};
    int nonQ1Products[1000] = {0};
    
    // Find products sold in Q1 2019
    for (int i = 0; i < saleCount; i++) {
        if (strcmp(sales[i].sale_date, "2019-01-01") >= 0 && 
            strcmp(sales[i].sale_date, "2019-03-31") <= 0) {
            q1Products[sales[i].product_id] = 1;
        }
    }
    
    // Find products sold outside Q1 2019
    for (int i = 0; i < saleCount; i++) {
        if (strcmp(sales[i].sale_date, "2019-01-01") < 0 || 
            strcmp(sales[i].sale_date, "2019-03-31") > 0) {
            nonQ1Products[sales[i].product_id] = 1;
        }
    }
    
    // Allocate result array
    Result* result = (Result*)malloc(productCount * sizeof(Result));
    *resultSize = 0;
    
    // Find products only in Q1
    for (int i = 0; i < productCount; i++) {
        int productId = products[i].product_id;
        if (q1Products[productId] && !nonQ1Products[productId]) {
            result[*resultSize].product_id = productId;
            strcpy(result[*resultSize].product_name, products[i].product_name);
            (*resultSize)++;
        }
    }
    
    return result;
}