Add minimax algorithm logic

Heuristic and game state definition still missing. No tests yet.

src/algorithms/ai/Minimax.js

@@ -0,0 +1,58 @@
+/**
+ *
+ * @param {*} node description of game state
+ * @param {Number} depth limit to the search depth
+ * @param {Number} player player id, either 0 or 1
+ * @returns game state resulting from the best found move
+ */
+function minimax(node, depth, player) {
+  if (depth === 0 || terminal_state(node)) {
+    return this.heuristic(node, player), node; // pretend there is a heuristic function supplies
+  }
+  opt = player == 0 ? Number.NEGATIVE_INFINITY : Number.POSITIVE_INFINITY;
+
+  opt_node = undefined;
+
+  for (const child in node.possibleStates()) { // pretend there is node.possibleStates
+    nextPlayer = player === 1 ? 0 : 1;
+
+    value, _ = minimax(move, depth - 1, nextPlayer);
+
+    if (player === 0) {
+      if (value < optimal) {
+        optimal = value;
+        opt_node = child;
+      }
+    } else {
+      if (value > optimal) {
+        optimal = value;
+        opt_node = child;
+      }
+    }
+  }
+  return optimal, opt_node;
+}
+
+/* inspired by Python...
+
+    def minimax(self, node: Node, depth: int, player: int):
+        if depth == 0 or self.is_terminal_state(node):
+            return self.h(node, player), node
+
+        opt = math.inf if (player != 0) else -math.inf
+        opt_node = None
+        for child in node.compute_and_get_children():
+            # test all possible moves
+            h, _ = self.minimax(child, depth-1, player ^ 1)
+            if player != 0:
+                if h > opt:
+                    opt = h
+                    opt_node = child
+            else:
+                if h < opt:
+                    opt = h
+                    opt_node = child
+
+        return opt, opt_node
+
+*/

src/algorithms/ai/__test__/Minimax.test.js

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+import Minimax from '../Minimax';
+
+describe('Minimax', () => {
+    
+    if('exists', () => {
+        expect(true);
+    });
+    
+});