1018. Binary Prefix Divisible By 5

QUESTION:

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

SOLUTION:

``````class Solution {
public List<Boolean> prefixesDivBy5(int[] A) {
boolean[] template = new boolean[]{true,false,false,false,false};
ArrayList<Boolean> result = new ArrayList<>();
int carry = 0;
for(int i = 0;i<A.length;i++){
carry = (2*carry + A[i])%5;
result.add(template[carry]);
}
return result;
}
}
``````
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