152. 乘积最大子序列

class Solution {
public:
   int max(int a, int b, int c) {
        int tmp;
        if (a > b) tmp = a;
        else tmp = b;
        if (tmp > c) return tmp;
        else return c;
    }
    int min(int a, int b, int c) {
        int tmp;
        if (a > b) tmp = b;
        else tmp = a;
        if (tmp > c) return c;
        else return tmp;
    }
    int maxProduct(vector<int>& nums) {
        if (nums.empty()) return 0;

        int pre_min, pre_max,res;
        pre_min = pre_max = res = nums[0];
        for (int i = 1; i < nums.size(); ++i) {
            int cur_max = max(nums[i] * pre_max, nums[i] * pre_min, nums[i]);
            int cur_min = min(nums[i] * pre_max, nums[i] * pre_min, nums[i]);
            if (cur_max > res) res = cur_max;
            pre_max = cur_max;
            pre_min = cur_min;
        }
        return res;
    }
};