86 lines
2.0 KiB
TypeScript
86 lines
2.0 KiB
TypeScript
import { getColor, isEmpty, isInside, setColorEmpty } from "./grid";
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import { around4 } from "./point";
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import { sortPush } from "./utils/sortPush";
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import type { Color, Grid } from "./grid";
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import type { Point } from "./point";
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type M = Point & { parent: M | null; h: number };
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const unwrap = (grid: Grid, m: M | null): Point[] =>
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m ? [...unwrap(grid, m.parent), m] : [];
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const getEscapePath = (
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grid: Grid,
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x: number,
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y: number,
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color: Color,
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forbidden: Point[] = []
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) => {
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const openList: M[] = [{ x, y, h: 0, parent: null }];
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const closeList: Point[] = [];
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while (openList.length) {
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const c = openList.shift()!;
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if (c.y === -1 || c.y === grid.height) return unwrap(grid, c);
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for (const a of around4) {
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const x = c.x + a.x;
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const y = c.y + a.y;
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if (!forbidden.some((cl) => cl.x === x && cl.y === y)) {
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if (!isInside(grid, x, y))
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return unwrap(grid, { x, y, parent: c } as any);
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const u = getColor(grid, x, y);
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if (
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(isEmpty(u) || u <= color) &&
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!closeList.some((cl) => cl.x === x && cl.y === y)
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) {
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const h = Math.abs(grid.height / 2 - y);
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const o = { x, y, parent: c, h };
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sortPush(openList, o, (a, b) => a.h - b.h);
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closeList.push(o);
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openList.push(o);
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}
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}
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}
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}
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return null;
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};
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const isFree = (
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grid: Grid,
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x: number,
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y: number,
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color: Color,
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snakeN: number
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) => {
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const one = getEscapePath(grid, x, y, color);
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if (!one) return false;
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const two = getEscapePath(grid, x, y, color, one.slice(0, snakeN));
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return !!two;
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};
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export const pruneLayer = (grid: Grid, color: Color, snakeN: number) => {
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const chunk: Point[] = [];
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for (let x = grid.width; x--; )
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for (let y = grid.height; y--; ) {
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const c = getColor(grid, x, y);
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if (!isEmpty(c) && c <= color && isFree(grid, x, y, color, snakeN)) {
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setColorEmpty(grid, x, y);
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chunk.push({ x, y });
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}
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}
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return chunk;
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};
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