暴力枚举

#include <iostream>
#include <vector>

using namespace std;

int n;

int main(void) {
  scanf("%d", &n);
  vector<int> h(n);
  for (int i = 0; i < n; ++i)
    cin >> h[i];

  int ans = 0;
  for (int i = 0; i < n; ++i) {
    int l = i, r = i;
    while (l >= 0 && h[l] >= h[i]) --l;
    while (r < n &&  h[r] >= h[i]) ++r;
    ans = max(ans, h[i] * (r - l - 1));
  }

   printf("%d\n", ans);
}