求最大子序列的乘积

最大子序列的乘积，两种方法:

1.方法一的时间复杂度为O(n^2),这个方法是通过循环遍历所有的子序列。

public static int maxSubMulti(int[] a){        int maxsub = 0;        int minsub = 0;        for(int i = 0 ; i < a.length ; i++){            int temp = 1;            for(int j = i; j < a.length; j++){                temp *= a[j];                if(temp > maxsub){                    maxsub = temp;                }                if(temp < minsub){                    minsub = temp;                }            }        }        return maxsub;    }

2.方法二是动态规划的方法。时间复杂度是O(N),通过求子序列（i,j）和a[i],的最大最小值，来更新序列的最大最小值。

public static int maxMulti(int[] a){        int[] maxsub = new int[a.length];        int[] minsub = new int[a.length];        maxsub[0] = a[0];        minsub[0] = a[0];        int maxval = maxsub[0];        for(int i = 1 ; i < a.length ; i++){            maxsub[i] = max3(a[i],maxsub[i - 1] * a[i],minsub[i - 1] * a[i]);            minsub[i] = min3(a[i],minsub[i - 1] * a[i],maxsub[i - 1] * a[i]);            if(maxval < maxsub[i]){                maxval = maxsub[i];            }        }        return maxval;    }