kings are 1.2x, not 2x. Fixed readme.

netanel-haber · May 27, 2023 · d5c3cd0 · d5c3cd0
1 parent 664839d
commit d5c3cd0
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Showing 4 changed files with 19 additions and 34 deletions.
diff --git a/README.md b/README.md
@@ -1,6 +1,6 @@
 # checkers
 
-[Play](https://netanel-haber.github.io/checkers/) vanilla TS, html and css pvp checkers started a trillion years ago, before I could tell a div from a span.
+[Play](https://netanel-haber.github.io/checkers/) vanilla TS, html and css checkers started a trillion years ago, before I could tell a div from a span.
 Now with Vite.
 
 **Features:**

diff --git a/index.html b/index.html
@@ -4,9 +4,9 @@
 <head>
     <meta charset="UTF-8">
     <meta http-equiv="X-UA-Compatible" content="IE=edge">
-    <meta name="description" content="PVP vanilla checkers, author: Netanel Haber">
+    <meta name="description" content="vanilla JS checkers, author: Netanel Haber">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
-    <title>PVP vanilla checkers</title>
+    <title>vanilla JS checkers</title>
     <link rel="preload" as="image" href="/red.webp" />
     <link rel="preload" as="image" href="/black.webp" />
     <link rel="preload" as="image" href="/red-king.webp" />

diff --git a/package.json b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "checkers",
   "version": "1.0.0",
-  "description": "pure js, html and css web based pvp checkers from a trillion years ago.  [Play](https://netanel-haber.github.io/checkers/).",
+  "description": "pure js, html and css web based checkers from a trillion years ago.  [Play](https://netanel-haber.github.io/checkers/).",
   "type": "module",
   "scripts": {
     "dev": "vite",
@@ -32,4 +32,4 @@
   "pre-commit": [
     "lint"
   ]
-}
+}
diff --git a/src/ai/engine.ts b/src/ai/engine.ts
@@ -4,41 +4,31 @@ import { type StateControllers } from "../types";
 
 import { forEachCell, gridValToColor } from "../utils";
 
+const valueToScore = [1, 1.2, 1, 1.2, 0] as const;
+
 export const calculateScore = ({ grid, turn }: BoardState) => {
   let score = 0;
   forEachCell((r, c) => {
     const cell = grid[r][c];
     const color = gridValToColor[cell];
     if (!color) return;
-    let value = 0;
-    switch (cell) {
-      case 0:
-      case 2:
-        value = 1;
-        break;
-      case 1:
-      case 3:
-        value = 2;
-    }
+    const value = valueToScore[cell];
     score += color === turn ? value : -value;
   });
   return score;
 };
 
-const DEPTH = 5;
+const ODD_DEPTH = 5;
+if (ODD_DEPTH % 2 === 0) {
+  throw new Error("Depth must be odd");
+}
 
-type BestMove = {
-  score: number;
-  move: {
-    finalRow: number;
-    finalColumn: number;
-    startRow: number;
-    startColumn: number;
-  };
+const defaultBest = {
+  score: 0,
+  move: { finalColumn: 0, finalRow: 0, startColumn: 0, startRow: 0 },
 };
-
 function bestMove(state: BoardState) {
-  function bestScore(state: BoardState, depth = DEPTH) {
+  function bestScore(state: BoardState, depth = ODD_DEPTH) {
     if (!depth) {
       return calculateScore(state);
     }
@@ -57,10 +47,7 @@ function bestMove(state: BoardState) {
     }
     return max;
   }
-  let best: BestMove = {
-    score: 0,
-    move: { finalColumn: 0, finalRow: 0, startColumn: 0, startRow: 0 },
-  };
+  let best = defaultBest;
   for (const [cell, potentialMoves] of state.getAllLegalMovesForColor()) {
     for (const { updates, finalCell } of potentialMoves) {
       const score = bestScore(state.updatedGrid(updates).updateCurrentTurn());
@@ -77,7 +64,7 @@ function bestMove(state: BoardState) {
       }
     }
   }
-  return best;
+  return best.move;
 }
 
 export const doAiMove = (
@@ -87,9 +74,7 @@ export const doAiMove = (
   if (state.turn !== COMPUTER) return;
   setTimeout(() => {
     const t0 = performance.now();
-    const {
-      move: { finalRow, finalColumn, startRow, startColumn },
-    } = bestMove(state);
+    const { finalRow, finalColumn, startRow, startColumn } = bestMove(state);
     const elapsed = performance.now() - t0;
     const maxiumum400 = Math.max(250 - elapsed, 0);
     setTimeout(() => {