leetcode-1488.js

var avoidFlood = function(rains) {
  const result = []
  const filled = new Set()
  return findSolution(rains, filled, result, 0)
};

function findSolution(rains, filled, result, day) {
  if (day >= rains.length) { // lo logramos!
    return result
  }
  
  if (rains[day] > 0 && filled.has(rains[day])) { // inundación!!!!!
    return []
  }
  
  if (rains[day] > 0) { // ese día llovió
    result[day] = -1
    filled.add(rains[day])
    return findSolution(rains, filled, [...result], day + 1)
  } else { // no llovió, tenemos que secar un lago
    if (filled.size === 0) { // no hay lagos llenos
      result[day] = 1
      return findSolution(rains, filled, [...result], day + 1)
    } else { // probar secando cada lago
      for (lake of filled) {
        const lakes = new Set(filled)
        lakes.delete(lake) // lo vamos a secar
        result[day] = lake
        const s = findSolution(rains, lakes, [...result], day + 1)
        if (s.length > 0) return s
      }
      return []
    }
  }
}

var avoidFlood = function(rains) {
  const filled = {}
  const noRain = []
  const result = []
  for (let i=0; i < rains.length; i++) {
    result.push(-1)
    if (rains[i] === 0) {
      noRain.push(i)
      result[i] = 0
    } else {
      if (filled[rains[i]] !== undefined) {
        if (noRain.length === 0) return []
        const from = filled[rains[i]]
        let found = false
        for (let j=0; j < noRain.length && !found; j++) {
          if (noRain[j] > from) {
            result[noRain[j]] = rains[i]
            noRain.splice(j, 1)
            found = true
          }
        }
        
        if (!found) return []
      } else {
        filled[rains[i]] = i
      }  
    }
  }
  
  for (let i=0; i < result.length; i++) {
    if (result[i] === 0) result[i] = 1
  }
  
  return result
};

Esta solución debería pasar por tiempo pero no está seleccionando bien el día de no lluvia.

Ya encontré el error, faltaba actualizar el último día de lluvia de ese lago!