title: Painting Fence Algorithm
signature: func paintingFenceAlgorithm(n int, k int) int {
test_code: package main
  
  import (
      "fmt"
      "reflect"
      "math"
      "sort"
  )
  
  // SOLUTION CODE
  // ===================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE
  // ===================================
  func validateSolution(actual int, expected int) bool {
      return reflect.DeepEqual(actual,expected)
  }
  
  func driver(n int, k int, expected int) string {
      if validateSolution(PLACEHOLDER_FN_NAME(n, k),expected) {
              return "PASSED"
      }
      return "FAILED"
  
  }
  
  func main() {
  
      // Use imports to avoid undefined errors
      var _ = reflect.DeepEqual
      _ = math.Abs
      _ = sort.Sort
      result := ""
      result = driver(6, 
  	30, 725841870)
      fmt.Printf("TEST-0...%s\n", result)
      
      result = driver(23, 
  	87, 370622679)
      fmt.Printf("TEST-1...%s\n", result)
      
      result = driver(89, 
  	31, 7554776)
      fmt.Printf("TEST-2...%s\n", result)
      
      result = driver(63, 
  	36, 76740139)
      fmt.Printf("TEST-3...%s\n", result)
      
      result = driver(23, 
  	68, 647498520)
      fmt.Printf("TEST-4...%s\n", result)
      
      result = driver(44, 
  	66, 70208793)
      fmt.Printf("TEST-5...%s\n", result)
      
      result = driver(81, 
  	18, 227130467)
      fmt.Printf("TEST-6...%s\n", result)
      
      result = driver(43, 
  	73, 204618786)
      fmt.Printf("TEST-7...%s\n", result)
      
      result = driver(9, 
  	42, 797370673)
      fmt.Printf("TEST-8...%s\n", result)
      
      result = driver(41, 
  	98, 903959704)
      fmt.Printf("TEST-9...%s\n", result)
      
          
  }
source_py: def painting_fence_algorithm(n, k):
      total = k
      mod = 1000000007
      (same, diff) = (0, k)
      for i in range(2, (n + 1)):
          same = diff
          diff = (total * (k - 1))
          diff = (diff % mod)
          total = ((same + diff) % mod)
      return total
source_cpp: long painting_fence_algorithm(int n, int k) {
    long total = k;
    int mod = 1000000007;
    int same = 0, diff = k;
    for ( int i = 2;
    i <= n;
    i ++ ) {
      same = diff;
      diff = total * ( k - 1 );
      diff = diff % mod;
      total = ( same + diff ) % mod;
    }
    return total;
  }