Skeleton and phase 1 of puzzle generation from a board

Only left and right vectors are computed for now.

board.h

@@ -42,7 +42,7 @@ class Board {
   Board(const int size, const BoardInitializer initializer);
 
   // Retrieves the board size.
-  int size() const;
+  int size() const { return size_; }
 
   // Returns the entry at the specified row and column. This could be
   // zero if the cell was never written to.

main.cc

@@ -23,7 +23,7 @@ int main(void) {
   Board b{5, BoardInitializer::DIAGONAL_INCREASING};
   b.print();
 
-  Puzzle p{5};
+  Puzzle p{b};
   p.print();
 
   return 0;

puzzle.cc

@@ -18,9 +18,25 @@
 
 #include "puzzle.h"
 
+#include "board.h"
 #include <cstdlib>
 #include <iostream>
 
+template <typename T>
+int compute_visibility(T begin, T end) {
+  int visible_cells = 0;
+  int highest_value = 0;
+
+  for (auto i = begin; i != end; ++i) {
+    if (*i > highest_value) {
+      highest_value = *i;
+      ++visible_cells;
+    }
+  }
+
+  return visible_cells;
+}
+
 Puzzle::Puzzle(const int size)
   : size_(size) {
   if (size_ <= 0) {
@@ -34,6 +50,25 @@ Puzzle::Puzzle(const int size)
   right_.resize(size_);
 }
 
+Puzzle::Puzzle(const Board& board) : Puzzle(board.size()) {
+#if 0
+  // Fill the top and bottom vectors
+  for (int column = 0; column < size_; ++column) {
+    top_[column] = compute_visibility(board.column_cbegin(column),
+                                      board.column_cend(column));
+    bottom_[column] = compute_visibility(board.column_crbegin(column),
+                                         board.column_crend(column));
+  }
+#endif
+  // Fill the left and right vectors
+  for (int row = 0; row < size_; ++row) {
+    left_[row] = compute_visibility(board.row_cbegin(row),
+                                    board.row_cend(row));
+    right_[row] = compute_visibility(board.row_crbegin(row),
+                                     board.row_crend(row));
+  }
+}
+
 void Puzzle::print() const {
   std::cout << "  ";
   for (const int v: top_) {

puzzle.h

@@ -27,7 +27,7 @@ class Puzzle {
   explicit Puzzle(const int size);
 
   // Creates a puzzle based on an existing, solved board.
-  explicit Puzzle(const Board &board);
+  explicit Puzzle(const Board& board);
 
   // Prints the puzzle to standard output.
   void print() const;