题解 | #连续子数组的最大乘积#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param nums int整型一维数组
     * @return int整型
     */
    public int maxProduct (int[] nums) {
        // write code here
        // 暴力破解
        /*
        int num = 0;
        int tmp = 1;
        int max = Integer.MIN_VALUE;
        for (int i = 1; i <= nums.length; i++) {
            num = nums[i - 1]; // 初始化
            for (int j = i; j >= 1; j--) {
                tmp *= nums[j - 1];
                num = Math.max(num, tmp);
            }
            tmp = 1;
            max = Math.max(max, num);
        }
        return max;
        */
        
        // 动态规划
        int previousMaximum = nums[0];
        int previousMinimum = nums[0];
        int currentMaximum = nums[0];
        int currentMinimum = nums[0];
        int rs = nums[0];
        for (int i = 2; i <= nums.length; i++) {
            currentMaximum = Math.max(Math.max(nums[i-1], previousMaximum*nums[i-1]), previousMinimum*nums[i-1]);
            currentMinimum = Math.min(Math.min(nums[i-1], previousMaximum*nums[i-1]), previousMinimum*nums[i-1]);
            rs = Math.max(rs, currentMaximum);
            previousMaximum = currentMaximum;
            previousMinimum = currentMinimum;
        }
        return rs;
    }
}