# 1018.Binary Prefix Divisible By 5

**1018.Binary Prefix Divisible By 5**

难度:Easy

> Given an array A of 0s and 1s, consider N\_i: the i-th subarray from A\[0] to A\[i] interpreted as a binary number (from most-significant-bit to least-significant-bit.)

Return a list of booleans answer, where answer\[i] is true if and only if N\_i is divisible by 5.

```
Example 1:

Input: [0,1,1]
Output: [true,false,false]
Explanation: 
The input numbers in binary are 0, 01, 011; which are 0, 1, and 3 in base-10.  Only the first number is divisible by 5, so answer[0] is true.
Example 2:

Input: [1,1,1]
Output: [false,false,false]
Example 3:

Input: [0,1,1,1,1,1]
Output: [true,false,false,false,true,false]
Example 4:

Input: [1,1,1,0,1]
Output: [false,false,false,false,false]
```

Note:

1 <= A.length <= 30000 A\[i] is 0 or 1

因为A的长度可能到30000，远超过了int表示的32位长度，因此直接相加肯定会溢出，可以在每次遍历时，将和置为其模5的值，因为往后遍历时，前面减掉的是5的倍数，后面每移一位，和乘2，也还是5的倍数，对结果没有影响。

```
class Solution {
public:
    vector<bool> prefixesDivBy5(vector<int>& A) {
        vector<bool> res;
        int tmp=0;
        for(auto i:A)
        {
            tmp=(tmp*2+i)%5;
            res.push_back(! (tmp));
        }
        return res;
    }
};
```

> 执行用时 :12 ms, 在所有 C++ 提交中击败了98.04%的用户\
> 内存消耗 :10.6 MB, 在所有 C++ 提交中击败了76.07%的用户


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://dfine.gitbook.io/leetcode/1018.binary_prefix_divisible_by_5.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.