🎯 Added solution for Real Image Challenge 2016

README.md

@@ -38,4 +38,7 @@ To submit a solution, fork this repo and send a Pull Request on Github.
 
 For any questions or clarifications, raise an issue on this repo and we'll answer your questions as fast as we can.
 
+---
 
+## Solution Guide
+For a detailed explanation of the solution, including usage instructions and enhancements, see [SOLUTION.md](./SOLUTION.md).

SOLUTION.md

@@ -0,0 +1,99 @@
+# Solution for Real Image Challenge 2016
+
+## Approach
+
+This solution implements a hierarchical permission system for movie distributors. In this system:
+
+1. **Data Loading**  
+   - We use `cities.csv` to validate region existence (cities, states, countries).  
+   - We use `distributors.csv` to dynamically build distributor permissions and hierarchy.
+
+2. **Normalization**  
+   - All inputs (distributor names, regions, etc.) are normalized to uppercase and stripped of spaces.  
+   - This ensures consistent matching, avoiding case and spacing issues.
+
+3. **Permission Checking**  
+   - A distributor's permissions are a subset of its parent's.  
+   - `EXCLUDE` rules override `INCLUDE` rules.  
+   - If a parent distributor excludes a region, all child distributors inherit that exclusion.
+
+4. **Authorization Logic**  
+   - We recursively check the distributor's parent permissions.  
+   - If the parent denies permission, the child is automatically denied.  
+   - If the region is explicitly excluded, deny permission.  
+   - If the region is included, allow permission.  
+   - Otherwise, deny.
+
+5. **Detailed Reasoning**  
+   - The solution provides reasons for why a distributor is authorized or not.
+
+---
+
+## Files
+
+- **`main.go`**: Main Go program that:
+  1. Loads CSV data
+  2. Accepts user input (distributor name + region)
+  3. Prints out authorization results
+
+- **`cities.csv`**: Contains the canonical list of city/state/country data.
+
+- **`distributors.csv`**: Lists each distributor's `INCLUDE`/`EXCLUDE` permissions and (optionally) a parent distributor.
+
+- **`SOLUTION.md`**: This file, explaining the approach in detail.
+
+---
+
+## Running the Program
+
+1. **Compile and Run**
+   ```bash
+    go run main.go
+   ```
+
+2. **When prompted**, enter:
+- **Distributor Name** (e.g., `DISTRIBUTOR1`)
+- **Region** in `CITY-STATE-COUNTRY` format (e.g., `CHICAGO-ILLINOIS-UNITED STATES`)
+
+
+## Expected Output
+
+The program will respond with either:
+```
+    DISTRIBUTOR1 is authorized to distribute in CHICAGO-ILLINOIS-UNITED STATES. Reason: Explicitly included by distributor: DISTRIBUTOR1
+```
+or
+```
+    DISTRIBUTOR1 is NOT authorized to distribute in CHICAGO-ILLINOIS-UNITED STATES. Reason: Explicitly excluded by distributor: DISTRIBUTOR1
+```
+
+---
+
+## Example
+Assuming the CSV data includes entries for `CHICAGO-ILLINOIS-UNITED STATES`:
+
+1. **Input**:
+    ```
+        Enter distributor name: DISTRIBUTOR1
+        Enter region (format CITY-STATE-COUNTRY): CHICAGO-ILLINOIS-UNITED STATES
+    ```
+2. **Output**:
+    ```
+    DISTRIBUTOR1 is authorized to distribute in CHICAGO-ILLINOIS-UNITED STATES. Reason: Explicitly included by distributor: DISTRIBUTOR1
+    ```
+
+---
+
+## Enhancements and Additional Features
+- **Detailed Reason** for authorization or denial.
+- **Hierarchy**: The solution recursively checks parent distributors.
+- **Dynamic Data**: No hardcoded distributor or region data.
+- **Normalization**: Minimizes errors due to case or spacing differences.
+- **Extended** to handle sub-distributors, ensuring they can't exceed their parent's permissions.
+
+---
+
+## Future Improvements
+- **Caching**: Use caching for repeated region checks.
+- **Advanced CLI**: Provide interactive commands to list distributors, visualize hierarchies, etc.
+- **Web API**: Expose the authorization logic over HTTP for an external service integration.

distributors.csv

@@ -0,0 +1,5 @@
+DistributorName,IncludeRegions(separated by |),ExcludeRegions(separated by |),ParentDistributor(optional)
+DISTRIBUTOR1,INDIA|UNITED STATES,KARNATAKA-INDIA|CHENNAI-TAMIL NADU-INDIA,
+DISTRIBUTOR2,INDIA,TAMIL NADU-INDIA,DISTRIBUTOR1
+DISTRIBUTOR3,HUBLI-KARNATAKA-INDIA,,DISTRIBUTOR2
+DISTRIBUTOR4,UNITED STATES,ALABAMA-UNITED STATES,DISTRIBUTOR1

main.go

@@ -0,0 +1,178 @@
+package main
+
+import (
+	"bufio"
+	"encoding/csv"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type Distributor struct {
+	Name    string
+	Include []string
+	Exclude []string
+	Parent  *Distributor
+}
+
+type City struct {
+	City    string
+	State   string
+	Country string
+}
+
+var cityMap map[string]City
+var distributors map[string]*Distributor
+
+func normalize(s string) string {
+	return strings.ToUpper(strings.ReplaceAll(strings.TrimSpace(s), " ", ""))
+}
+
+func loadCities(path string) {
+	file, err := os.Open(path)
+	if err != nil {
+		panic(err)
+	}
+	defer file.Close()
+
+	reader := csv.NewReader(file)
+	records, err := reader.ReadAll()
+	if err != nil {
+		panic(err)
+	}
+
+	cityMap = make(map[string]City)
+	for _, rec := range records[1:] {
+		cityKey := normalize(rec[3] + "-" + rec[4] + "-" + rec[5])
+		cityMap[cityKey] = City{
+			City:    normalize(rec[3]),
+			State:   normalize(rec[4]),
+			Country: normalize(rec[5]),
+		}
+	}
+}
+
+func loadDistributors(path string) {
+	file, err := os.Open(path)
+	if err != nil {
+		panic(err)
+	}
+	defer file.Close()
+
+	reader := csv.NewReader(file)
+	records, err := reader.ReadAll()
+	if err != nil {
+		panic(err)
+	}
+
+	distributors = make(map[string]*Distributor)
+	for _, rec := range records[1:] {
+		name := normalize(rec[0])
+		includes := strings.Split(rec[1], "|")
+		excludes := strings.Split(rec[2], "|")
+		parentName := normalize(rec[3])
+		var parent *Distributor
+		if parentName != "" {
+			parent = distributors[parentName]
+		}
+		for i := range includes {
+			includes[i] = normalize(includes[i])
+		}
+		for i := range excludes {
+			excludes[i] = normalize(excludes[i])
+		}
+		distributors[name] = &Distributor{
+			Name:    name,
+			Include: includes,
+			Exclude: excludes,
+			Parent:  parent,
+		}
+	}
+}
+
+func isAuthorized(dist *Distributor, region string) (bool, string) {
+	region = normalize(region)
+
+	if !regionExists(region) {
+		return false, "Region does not exist"
+	}
+
+	if dist.Parent != nil {
+		parentAuthorized, _ := isAuthorized(dist.Parent, region)
+		if !parentAuthorized {
+			return false, "Denied by parent distributor: " + dist.Parent.Name
+		}
+	}
+
+	for _, ex := range dist.Exclude {
+		if matchesRegion(region, ex) {
+			return false, "Explicitly excluded by distributor: " + dist.Name
+		}
+	}
+
+	for _, inc := range dist.Include {
+		if matchesRegion(region, inc) {
+			return true, "Explicitly included by distributor: " + dist.Name
+		}
+	}
+
+	return false, "No matching inclusion found"
+}
+
+
+func matchesRegion(query, perm string) bool {
+	qParts := strings.Split(query, "-")
+	pParts := strings.Split(perm, "-")
+
+	if len(qParts) < len(pParts) {
+		return false
+	}
+
+	for i := 1; i <= len(pParts); i++ {
+		if qParts[len(qParts)-i] != pParts[len(pParts)-i] {
+			return false
+		}
+	}
+	return true
+}
+
+func regionExists(region string) bool {
+	_, cityOk := cityMap[region]
+	if cityOk {
+		return true
+	}
+	for city := range cityMap {
+		if strings.HasSuffix(city, region) {
+			return true
+		}
+	}
+	return false
+}
+
+func main() {
+	loadCities("cities.csv")
+	loadDistributors("distributors.csv")
+
+	scanner := bufio.NewScanner(os.Stdin)
+
+	fmt.Print("Enter distributor name: ")
+	scanner.Scan()
+	distName := normalize(scanner.Text())
+
+	dist, exists := distributors[distName]
+	if !exists {
+		fmt.Printf("Distributor %s not found\n", distName)
+		return
+	}
+
+	fmt.Print("Enter region (format CITY-STATE-COUNTRY): ")
+	scanner.Scan()
+	region := normalize(scanner.Text())
+
+	authorized, reason := isAuthorized(dist, region)
+	if authorized {
+		fmt.Printf("%s is authorized to distribute in %s. Reason: %s\n", dist.Name, region, reason)
+	} else {
+		fmt.Printf("%s is NOT authorized to distribute in %s. Reason: %s\n", dist.Name, region, reason)
+	}
+}