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Merge pull request #6 from nosnaws/better-heuristics
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improve heuristics
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@nosnaws
nosnaws authored Feb 27, 2022
2 parents f6e3ea5 + 6222f54 commit c9c7e4c
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Showing 5 changed files with 365 additions and 80 deletions.
51 changes: 40 additions & 11 deletions src/logic.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -35,8 +35,32 @@ export function move(state: GameState): MoveResponse {
}

const getMoveResponse = (location: Coord, state: GameState): MoveResponse => {
const neighbors = getPossibleMoves(state.you.head, state.board);
const width = state.board.width;
const height = state.board.height;
const you = state.you;
const neighbors = [
{ x: you.head.x - 1, y: you.head.y, dir: "left" },
{ x: you.head.x + 1, y: you.head.y, dir: "right" },
{ x: you.head.x, y: you.head.y - 1, dir: "down" },
{ x: you.head.x, y: you.head.y + 1, dir: "up" },
]
.map(({ x, y, dir }) => ({
x: x % width,
y: y % height,
dir,
}))
.map(({ x, y, dir }) => {
if (x < 0) {
x = width - 1;
}
if (y < 0) {
y = height - 1;
}
return { x, y, dir };
});

if (location) {
log(neighbors);
const [move] = neighbors.filter(isCoordEqual(location));

if (move) {
Expand All @@ -47,14 +71,19 @@ const getMoveResponse = (location: Coord, state: GameState): MoveResponse => {
return { move: "left" };
};

interface Move extends Coord {
dir: string;
}
//interface Move extends Coord {
//dir: string;
//}

//const getPossibleMoves = (location: Coord, { height, width }: Board): Move[] =>
//[
//{ x: location.x - 1, y: location.y, dir: "left" },
//{ x: location.x + 1, y: location.y, dir: "right" },
//{ x: location.x, y: location.y - 1, dir: "down" },
//{ x: location.x, y: location.y + 1, dir: "up" },
//].map(({ x, y, dir }) => {
//if (x < 0) {
//x =
//}

const getPossibleMoves = (location: Coord, { height, width }: Board): Move[] =>
[
{ x: location.x - 1, y: location.y, dir: "left" },
{ x: location.x + 1, y: location.y, dir: "right" },
{ x: location.x, y: location.y - 1, dir: "down" },
{ x: location.x, y: location.y + 1, dir: "up" },
].map(({ x, y, dir }) => ({ x: x % width, y: y % height, dir }));
//}({ x: x % width, y: y % height, dir }));
121 changes: 78 additions & 43 deletions src/lookahead_snake.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ import {

import { log } from "./utils/general";
import { createQueue, Queue } from "./utils/queue";
const coordStr = (c: Coord) => `${c?.x},${c?.y}`;

export const voronoi = (gs: GameStateSim): number => {
interface Pair {
Expand Down Expand Up @@ -270,18 +271,9 @@ const nodeHeuristic = (

const stateHeuristic = (gs: GameStateSim): number => {
const { you, board, turn, grid } = gs;
const headNode = grid[you.head.y][you.head.x];
const otherSnakes = gs.board.snakes.filter((s) => s.id !== gs.you.id);

let total = 0;
const isHead = isCoordEqual(you.head);
const snakesWithMoves: {
snake: Battlesnake;
possibleMoves: Node[];
}[] = otherSnakes.map((s) => ({
snake: s,
possibleMoves: getMoves(grid, s.body, gs.isWrapped),
}));

if (didWeWinBoys(gs, you)) {
//printGrid(gs.grid);
Expand All @@ -295,55 +287,61 @@ const stateHeuristic = (gs: GameStateSim): number => {
return -Infinity;
}

total += 10000 / board.snakes.length ?? 1;
total += 10000 / otherSnakes.length ?? 1;
const foodPaths = board.food
.map((f) => BFS(grid, you.head, f))
.sort((a, b) => a.length - b.length);
const a = 40; // much hungrier in the beginning
const b = 2;
for (let i = 0; i < 3; i++) {
const a = -60; // much hungrier in the beginning
const b = 1;
for (let i = 0; i < foodPaths.length; i++) {
const foodPath = foodPaths[i];
if (foodPath) {
total += a * Math.atan(you.health - foodPath.length / b);
}
}
//foodPaths.forEach((foodPath) => {
//// TODO: handle hazards when there isn't food, could also factor in the number of hazard spaces on the path
////const foodDistanceCost = headNode.hasHazard ? 16 : 1;
//total += a * Math.atan(you.health - foodPath.length / b);
//});
//if (headNode.hasFood) {
//total += 100;
//}

const voronoiScore = voronoi(gs);

log(`voronoi for ${you.head.x},${you.head.y} score:${voronoiScore}`);
//log(`voronoi for ${you.head.x},${you.head.y} score:${voronoiScore}`);
if (voronoiScore) {
total += voronoiScore * 10; // should be a hyper parameter
total += voronoiScore * 1; // should be a hyper parameter
}

//log(`head:${you.head.x},${you.head.y} total:${total}`);
return total;
};

const pathHeuristic = (gs: GameStateSim, move: Coord): number => {
const { you, grid } = gs;
const otherSnakes = gs.board.snakes.filter((s) => s.id !== gs.you.id);
const moveNode = grid[move.y][move.x];

let total = 0;
const isMove = isCoordEqual(move);
const snakesWithMoves: {
snake: Battlesnake;
possibleMoves: Node[];
}[] = otherSnakes.map((s) => ({
snake: s,
possibleMoves: getMoves(grid, s.body, gs.isWrapped),
}));

for (const pm of snakesWithMoves) {
if (pm.possibleMoves.map(prop("coord")).some(isHead)) {
if (pm.possibleMoves.map(prop("coord")).some(isMove)) {
if (pm.snake.length >= you.length) {
log(`possible death move:${you.head.x},${you.head.y}`);
total = -10000;
}
if (pm.snake.length < you.length) {
total = total * 1000;
log(`possible death move:${coordStr(move)}`);
total += -10000000; //change this since it's just a possible move
}
}
}

if (headNode.hasHazard) {
total += -Math.atan(you.health / 16);
if (moveNode.hasHazard) {
total += -Math.atan(you.health / 5);
}

if (headNode.hasSnakeTail && hasDuplicates(headNode.snake?.body ?? [])) {
if (moveNode.hasSnakeTail && hasDuplicates(moveNode.snake?.body ?? [])) {
total = -Infinity;
}

log(`head:${you.head.x},${you.head.y} total:${total}`);
return total;
};

Expand Down Expand Up @@ -387,18 +385,40 @@ export const alphabeta = (
if (maximizingPlayer) {
let value = -Infinity;

for (const pm of getMoves(grid, you.body, isWrapped)) {
const n = getMoves(grid, you.body, isWrapped);
log(`moves at depth:${depth}`);
log(n);
for (const pm of n) {
const ns = cloneGameState(gs);
log(`testing move:${pm.coord.x},${pm.coord.y}`);
log(`testing move:${coordStr(pm.coord)} depth:${depth}`);
addMove(ns, you, pm.coord);

const moveH = stateHeuristic(ns);
const moveH = pathHeuristic(ns, pm.coord);
const min = alphabeta(ns, pm.coord, depth - 1, alpha, beta, false);

//const = moveH + Math.max(value, next.score);

if (moveH < 0) {
value = moveH;
log(
`moveH override for ${coordStr(
pm.coord
)} depth:${depth} move:${coordStr(move)}`
);
min.score = moveH;
}

log(
`comparing score:${value} move:${coordStr(move)} to score:${
min.score
} move:${coordStr(min.move)} depth:${depth}`
);
if (min.score > value) {
log(
`taking higher score:${min.score} move:${coordStr(
min.move
)} depth:${depth}`
);
log(`setting move to parent:${coordStr(pm.coord)}`);
value = min.score;
move = pm.coord;
}
Expand All @@ -409,6 +429,9 @@ export const alphabeta = (
alpha = Math.max(alpha, value);
}
//log({ score: value, move });
log(`return max score:${value} move:${coordStr(move)} depth:${depth}`);
//
// TODO: if all the moves are terrible, it can return it's own head
return { score: value, move };
} else {
let value = Infinity;
Expand All @@ -421,11 +444,15 @@ export const alphabeta = (
addMove(ns, enemy, pm.coord);

const nextTurn = resolveTurn(ns);
const max = alphabeta(nextTurn, pm.coord, depth - 1, alpha, beta, true);
const max = alphabeta(nextTurn, move, depth - 1, alpha, beta, true);
//value = Math.min(value, max.score);
if (max.score < value) {
log(
`taking lower score:${max.score} move:${coordStr(
max.move
)} depth:${depth}`
);
value = max.score;
move = pm.coord;
}
if (value <= alpha) {
log(`min prunning`);
Expand All @@ -446,6 +473,7 @@ export const alphabeta = (
beta = Math.min(beta, value);
}

log(`return max score:${value} move:${coordStr(move)} depth:${depth}`);
return { score: value, move };
}
};
Expand All @@ -455,7 +483,7 @@ export const determineMove = (state: GameState, depth: number = 2): Coord => {
const isWrapped = state.game.ruleset.name === "wrapped";
const grid = createGrid(board);
const ns = cloneGameState({ ...state, pendingMoves: [], isWrapped, grid });

log(`starting ${state.game.ruleset.name} game`);
//const perms = createGameStatePermutations(ns);

//const [bestMove, ...rest] = perms
Expand All @@ -466,7 +494,14 @@ export const determineMove = (state: GameState, depth: number = 2): Coord => {
//};
//})
//.sort((a, b) => b.score - a.score);

//const moves = getMoves(grid, ns.you.body, isWrapped)
//.map((m) => {
//log(m.coord);
//return m;
//})
//.map((m) => alphabeta(ns, m.coord, depth, -Infinity, Infinity, true))
//.sort((a, b) => b.score - a.score);
const move = alphabeta(ns, ns.you.head, depth, -Infinity, Infinity, true);
return move.move;
log(move);
return move?.move;
};
20 changes: 15 additions & 5 deletions src/utils/board.ts
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
import { Battlesnake, Board, Coord, Ruleset } from "../types";
import { prop } from "./general";
import { log, prop } from "./general";
import { createQueue } from "./queue";

export interface Node {
Expand Down Expand Up @@ -138,10 +138,20 @@ export const adjustForWrapped = (
height: number,
width: number
): Coord[] =>
coords.map(({ x, y }) => ({
x: x % width,
y: y % height,
}));
coords
.map(({ x, y }) => ({
x: x % width,
y: y % height,
}))
.map(({ x, y }) => {
if (x < 0) {
x = width - 1;
}
if (y < 0) {
y = height - 1;
}
return { x, y };
});

export const isInArray = (coords: Coord[]) => (l: Coord): boolean =>
coords.some(isCoordEqual(l));
Expand Down
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