Solution.cs

public class Solution {
    public int MaxProduct(int[] nums) {
        int f = nums[0], g = nums[0], ans = nums[0];
        for (int i = 1; i < nums.Length; ++i) {
            int ff = f, gg = g;
            f = Math.Max(nums[i], Math.Max(ff * nums[i], gg * nums[i]));
            g = Math.Min(nums[i], Math.Min(ff * nums[i], gg * nums[i]));
            ans = Math.Max(ans, f);
        }
        return ans;
    }
}