Codility: Peaks Solution

Implementation

1function solution(A) {
2  const N = A.length
3  const isPeak = (a, b, c) => a < b && b > c
4
5  const peaks = []
6  for (let i = 1; i < N - 1; i++) {
7    if (isPeak(A[i - 1], A[i], A[i + 1])) {
8      peaks.push(i)
9    }
10  }
11
12  for (let blockSize = 1; blockSize <= N; blockSize++) {
13    if (N % blockSize !== 0) {
14      continue
15    }
16    let quotient = 0
17    const numberOfBlocks = Math.floor(N / blockSize)
18    let valid = true
19    for (const peakIndex of peaks) {
20      if (Math.floor(peakIndex / blockSize) === quotient) {
21        quotient++
22      }
23    }
24
25    // make sure each block have at least 1 peak
26    if (quotient !== numberOfBlocks) {
27      valid = false
28    }
29    if (valid) return numberOfBlocks
30  }
31  return 0
32}

References

https://rafal.io/posts/codility-peaks.html