From 6add626470333fec017a580cc8fdcc8a489359de Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Sun, 28 Feb 2021 14:41:26 -0500
Subject: [PATCH] Flesh out Solver a bit more.

Something is definitely broken though...
---
 src/main.d        |   9 +++++
 src/pegp/board.d  |   2 +
 src/pegp/solver.d | 101 ++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 109 insertions(+), 3 deletions(-)

diff --git a/src/main.d b/src/main.d
index 6f84c44..450cb4f 100644
--- a/src/main.d
+++ b/src/main.d
@@ -1,6 +1,15 @@
 import std.stdio;
+import pegp.solver;
 
 int main(string[] args)
 {
+    version (unittest)
+    {
+    }
+    else
+    {
+        Solver s = new Solver(3);
+        s.solve();
+    }
     return 0;
 }
diff --git a/src/pegp/board.d b/src/pegp/board.d
index 4bd59b0..9d60e5b 100644
--- a/src/pegp/board.d
+++ b/src/pegp/board.d
@@ -9,11 +9,13 @@ class Board
     enum Direction
     {
         NW,
+        FIRST = NW,
         NE,
         W,
         E,
         SW,
         SE,
+        COUNT,
     }
 
     struct Position
diff --git a/src/pegp/solver.d b/src/pegp/solver.d
index cca4068..eb7603a 100644
--- a/src/pegp/solver.d
+++ b/src/pegp/solver.d
@@ -1,17 +1,112 @@
 module pegp.solver;
 
 import pegp.board;
+import std.stdio;
 
 class Solver
 {
-    Board m_board;
+    class Move
+    {
+        Board.Position m_source;
+        Board.Position m_dest;
+
+        this(Board.Position source, Board.Position dest)
+        {
+            m_source = source;
+            m_dest = dest;
+        }
+
+        @property Board.Position source()
+        {
+            return m_source;
+        }
+
+        @property Board.Position dest()
+        {
+            return m_dest;
+        }
+    }
+
+    int m_size;
+    int m_game_count;
+    int m_1_peg_game_count;
+    int m_1_peg_corner_game_count;
+    Move[] m_1_peg_corner_moves;
 
     this(int size)
     {
-        m_board = new Board(size);
+        m_size = size;
     }
 
-    static void solve()
+    void solve()
     {
+        Board board = new Board(m_size);
+        Move[] moves;
+        eval_board(board, moves);
+        report();
+    }
+
+    void eval_board(Board board, Move[] moves)
+    {
+        bool found_valid_move = false;
+        for (int row = 0; row < m_size; row++)
+        {
+            for (int col = 0; col < row; col++)
+            {
+                for (Board.Direction direction = Board.Direction.FIRST;
+                     direction < Board.Direction.COUNT;
+                     direction++)
+                {
+                    Board.Position position = Board.Position(row, col);
+                    Board new_board = board.move(position, direction);
+                    if (new_board !is null)
+                    {
+                        found_valid_move = true;
+                        Move m = new Move(position, position.move(direction, 2));
+                        Move[] new_moves = moves.dup;
+                        new_moves ~= m;
+                        eval_board(new_board, new_moves);
+                    }
+                }
+            }
+        }
+        if (!found_valid_move)
+        {
+            end_game(board, moves);
+        }
+    }
+
+    void end_game(Board board, Move[] moves)
+    {
+        m_game_count++;
+        if (board.peg_count == 1)
+        {
+            m_1_peg_game_count++;
+            if (board.peg_present(0, 0) ||
+                board.peg_present(m_size - 1, 0) ||
+                board.peg_present(m_size - 1, m_size - 1))
+            {
+                m_1_peg_corner_game_count++;
+                if (m_1_peg_corner_moves is null)
+                {
+                    m_1_peg_corner_moves = moves;
+                }
+            }
+        }
+    }
+
+    void report()
+    {
+        writeln("Played ", m_game_count, " games.");
+        writeln(m_1_peg_game_count, " of them had 1 peg left.");
+        writeln(m_1_peg_corner_game_count, " of them had the 1 peg left in a corner.");
+        if (m_1_peg_corner_moves !is null)
+        {
+            writeln("Here is one such move sequence:");
+            foreach (move; m_1_peg_corner_moves)
+            {
+                writeln(" ", move.source, " -> ", move.dest);
+            }
+        }
     }
 }