n0mbers/src/algo.ts

import { operators, pool } from './globals'
import { OperatorType } from './types'
import { randRange } from './utils'

type HistoryType = { a: number; b: number; op: OperatorType }[]

export function operate(operator: OperatorType, valA: number, valB: number): number {
  switch (operator) {
    case '+':
      return valA + valB
    case '-':
      return valA - valB
    case '*':
      return valA * valB
    case '/':
      return valA / valB
  }
}

export function isSolvable(result: number, plaquettes: number[]): boolean {
  function printHistory(history: HistoryType): void {
    for (const item of history) {
      if (item.a < item.b) [item.a, item.b] = [item.b, item.a]
      console.log(
        `${item.a} ${item.op} ${item.b} = ${operate(item.op, item.a, item.b)}`,
      )
    }
    console.log()
  }

  function loopOperations(plaquettes: number[], history: HistoryType): void {
    for (let i = 0; i < plaquettes.length - 1; ++i) {
      for (let j = i + 1; j < plaquettes.length; ++j) {
        let a = plaquettes[i]
        let b = plaquettes[j]
        if (a < b) [a, b] = [b, a]
        for (const op of operators) {
          if (op === '/' && a % b !== 0) continue
          recursOperation(op, a, b, plaquettes, history)
        }
      }
    }
  }

  function recursOperation(
    operator: OperatorType,
    valA: number,
    valB: number,
    oldPlaquettes: number[],
    oldHistory: HistoryType,
  ): void {
    if (found) return
    if (new Date().getTime() - startTime.getTime() > 250) return

    const plaquettes = [...oldPlaquettes]
    const history = [...oldHistory]

    // remove values from plaquettes
    const idxA = plaquettes.findIndex(p => p === valA)
    plaquettes.splice(idxA, 1)
    const idxB = plaquettes.findIndex(p => p === valB)
    plaquettes.splice(idxB, 1)

    // calculate result and push it into plaquettes
    const r = operate(operator, valA, valB)
    plaquettes.push(r)

    // Save step
    history.push({ a: valA, b: valB, op: operator })

    // Found the solution
    if (plaquettes.indexOf(result) > -1) {
      histories.push(history)
      if (!found) {
        found = true
        console.log('1e solution trouvée en ' + (Date.now() - start) + 'ms')
      }
      return
    }
    // Exhausted all plaquettes
    else if (plaquettes.length === 1) {
      return
    }

    loopOperations(plaquettes, history)
  }

  const histories: HistoryType[] = []

  // Start calculations
  const start = Date.now()
  let found = false
  const startTime = new Date()
  loopOperations(plaquettes, [])

  if (histories.length) {
    printHistory(histories[0])
  }
  console.log(new Date().getTime() - startTime.getTime() + 'ms')

  return found

  // histories.sort((a, b) => a.length - b.length)
  // console.log(
  //   `${histories.length} combinaisons trouvées en ${Date.now() - start}ms`,
  // ) // Entre 18 et 1410
  // if (histories.length) {
  //   console.log()
  //   printHistory(histories[0])
  // }
}