aoc21_13.js

import { accessSync, promises as fs } from 'fs';



(async()=>{
    const input = await fs.readFile("./interpretertests/aoc_21_13_input.txt", 'utf8')

    const p = (grid) => {
        for (let y = 0; y < grid.length; y++) {
            console.log(grid[y].map(x=>x==0?'.':'#').join(''))
        }
        console.log('\n\n')
    }

    const fy = (grid, yf) => {
        const nl = yf<grid.length/2?grid.length-yf-1:yf
        let newGrid = Array.apply(null, Array(nl)).map(()=>Array.apply(null, Array(grid[0].length)).map(()=>0))
        
        for (let y = 0; y < yf; y++) {
            for (let x = 0; x < grid[y].length; x++) {
                newGrid[y][x] = grid[y][x]
            }
        }

        for (let y = yf+1; y < grid.length; y++) {
            const yc = yf-(y-yf)
            
            for (let x = 0; x < grid[y].length; x++) {
                if (grid[y][x]) newGrid[yc][x] = grid[y][x]
            }
        }
        
        return newGrid
    }

    const fx = (grid, xf) => {
        const nl = xf<grid[0].length/2?grid[0].length-xf-1:xf
        let newGrid = Array.apply(null, Array(grid.length)).map(()=>Array.apply(null, Array(nl)).map(()=>0))

        for (let y = 0; y < grid.length; y++) {
            for (let x = 0; x < xf; x++) {
                newGrid[y][x] = grid[y][x]
            }
        }

        for (let y = 0; y < grid.length; y++) {
            for (let x = xf+1; x < grid[y].length; x++) {
                const xc = xf-(x-xf)
                if (grid[y][x]) newGrid[y][xc] = grid[y][x]
            }
        }
        return newGrid

    }

    const cd = (grid) => {
        return grid.reduce((acc, row)=>acc+row.reduce((acc, x)=>acc+x, 0), 0)
    }

    const mapping = input.split('\n').reduce((a,c)=>{
        if (c.trim()=='') {
            a.space = true
        } else if (!a.space) {
            const xy = c.trim().split(',').map(Number)
            a.coords.push(xy)
            if(xy[0]>a.max[0]) a.max[0] = xy[0]
            if(xy[1]>a.max[1]) a.max[1] = xy[1] 
        } else {
            const sp = c.trim().split('=')
            a.folds.push([sp[0].endsWith('x'), parseInt(sp[1])])
        }
        return a
    }, {coords: [], folds: [], space: false, max: [0,0]}) 

    let grid = Array.apply(null, Array(mapping.max[1]+1)).map(()=>Array.apply(null, Array(mapping.max[0]+1)).map(()=>0))

    for (let i=0; i<mapping.coords.length; i++) {
        const xy = mapping.coords[i]
        grid[xy[1]][xy[0]] = 1
    }

    console.log('#1', cd(fx(grid, mapping.folds[0][1])))

    for (let f of mapping.folds) {
        if (f[0]) {
            grid = fx(grid, f[1])
        } else {
            grid = fy(grid, f[1])
        }
        
    }
    console.log('#2')
    p(grid)
   
})()