solve.cpp

#include <vector>
#include <climits>
#include <cstdlib>
#include <cstdio>
#define MAX(a, b) ((a) >= (b) ? (a) : (b))
#define MIN(a, b) ((a) <= (b) ? (a) : (b))
using namespace std;
class Solution {
public:
    int maxProduct(vector<int>& nums) {
	    const size_t size = nums.size();
	    if (size < 1)
		    return 0;
	    if (size == 1)
		    return nums[0];
	    int neg = 0, pos = 0, max = 0;
	    for (auto i = 0; i < size; ++i) {
		    if (nums[i] == 0) {
			    pos = neg = 0;
		    } else if (nums[i] > 0) {
			    pos = MAX(pos * nums[i], nums[i]);
			    neg = MIN(neg * nums[i], neg);
		    } else {
			    int old_pos = pos;
			    int old_neg = neg;
			    pos = MAX(old_neg * nums[i], nums[i]);
			    neg = MIN(old_pos * nums[i], nums[i]);
		    }
		    max = MAX(max, pos);
	    }
	    return max;
    }
};
int main(int argc, char **argv)
{
	Solution solution;
	int a[20];
	int n;
	while (scanf("%d", &n) != EOF) {
		for (int i = 0; i < n; ++i)
			scanf("%d", a + i);
		vector<int> v(a, a + n);
		printf("%d\n", solution.maxProduct(v));
	}
}