Umbrella.js

umbrella.js

//Solution of https://gist.github.com/lubien/1f09a53a4b5607377166c58a7eb49ae0

const solve = (people, umbrellas) => {
    const biggerUmbrella = Math.max(...umbrellas)
    const remain = people % biggerUmbrella
    const peopleThatFit = Math.floor(people / biggerUmbrella)

    if (remain >= 1 && umbrellas.length === 1) {
        return -1
    } else {
        const remainingUmbrellas = umbrellas.filter(umbrella => umbrella !== biggerUmbrella)
        return remain !== 0 ? solve(remain, remainingUmbrellas) + peopleThatFit : peopleThatFit
    }
}

const tests =
[ { n: 3
  , umbrellas: [1, 2]
  , expect: 2
  }
  
, { n: 10
  , umbrellas: [3, 1]
  , expect: 4
  }

, { n: 3
  , umbrellas: [2]
  , expect: -1
  }
]

tests.forEach(({n, umbrellas, expect}) =>
  console.log(`solve(${n}, [${umbrellas}])`)        ||
  console.log(`   Expects: ${expect}`)              ||
  console.log(`   Output:  ${solve(n, umbrellas)}`) ||
  console.log()
)