Given an array A
of integers, return the number of (contiguous, non-empty) subarrays that have a sum divisible by K
.
Example 1:
Input: A = [4,5,0,-2,-3,1], K = 5 Output: 7 Explanation: There are 7 subarrays with a sum divisible by K = 5: [4, 5, 0, -2, -3, 1], [5], [5, 0], [5, 0, -2, -3], [0], [0, -2, -3], [-2, -3]
Note:
1 <= A.length <= 30000
-10000 <= A[i] <= 10000
2 <= K <= 10000
struct Solution;
impl Solution {
fn subarrays_div_by_k(a: Vec<i32>, k: i32) -> i32 {
let n = k as usize;
let mut count: Vec<i32> = vec![0; n];
let mut sum = 0;
let mut res = 0;
count[0] = 1;
for x in a {
sum = (sum + x % k + k) % k;
res += count[sum as usize];
count[sum as usize] += 1;
}
res
}
}
#[test]
fn test() {
let a = vec![4, 5, 0, -2, -3, 1];
let k = 5;
let res = 7;
assert_eq!(Solution::subarrays_div_by_k(a, k), res);
}