09 Sept 2026•Go / Python / TypeScript•Easy

Binary Prefix Divisible By 5

Report whether each binary-array prefix represents a number divisible by five.

Update only the prefix remainder modulo five as each bit arrives; divisibility depends on that remainder, not the full potentially large number.

complexity

O(n) time and O(n) output space.

solution files

Go binary-prefix-divisible-by-5/solution.go
Python binary-prefix-divisible-by-5/solution.py
TypeScript binary-prefix-divisible-by-5/solution.ts

Solution files

Go•binary-prefix-divisible-by-5/solution.go

package main

func prefixesDivBy5(nums []int) []bool {
	result := make([]bool, len(nums))
	remainder := 0
	for index, bit := range nums {
		remainder = (remainder*2 + bit) % 5
		result[index] = remainder == 0
	}
	return result
}

Python•binary-prefix-divisible-by-5/solution.py

class Solution:
    def prefixesDivBy5(self, nums: list[int]) -> list[bool]:
        result: list[bool] = []; remainder = class="syntax-number">0
        for bit in nums:
            remainder = (remainder * class="syntax-number">2 + bit) % class="syntax-number">5
            result.append(remainder == class="syntax-number">0)
        return result

TypeScript•binary-prefix-divisible-by-5/solution.ts

function prefixesDivBy5(nums: number[]): boolean[] {
  const result: boolean[] = []; let remainder = class="syntax-number">0;
  for (const bit of nums) { remainder = (remainder * class="syntax-number">2 + bit) % class="syntax-number">5; result.push(remainder === class="syntax-number">0); }
  return result;
}