*[codility]Peaks

https://codility.com/demo/take-sample-test/peaks

http://blog.csdn.net/caopengcs/article/details/17491791

其实可以做到O(n)

#include <iostream>
#include <sstream>
using namespace std;

int solution(vector<int> &A) {
    int n = A.size();
    int prevPeak = -1;
    int maxDist = -1;
    vector<int> peaks(n);
    for (int i = 0; i < n; i++) {
        if (i == 0) {
            peaks[i] = 0;
        } else if (i == n - 1) {
            peaks[i] = peaks[i - 1];
        } else if (A[i] > A[i - 1] && A[i] > A[i + 1]) {
            peaks[i] = peaks[i - 1] + 1;
            if (prevPeak == -1) {
                prevPeak = i;
            } else {
                maxDist = max(maxDist, i - prevPeak);
                prevPeak = i;
            }
        } else {
            peaks[i] = peaks[i - 1];
        }
    }
    if (peaks[n - 1] == 0) return 0;
    if (peaks[n - 1] == 1) return 1;
    for (int dist = maxDist / 2; dist <= n; dist++) {
        if (n % dist != 0)
            continue;
        bool found = true;
        for (int i = n - 1; i - dist > 0; i -= dist) {
            if (peaks[i] == peaks[i - dist]) {
                found = false;
                break;
            }
        }
        if (found) return n / dist;
    }
    return 0;
}