Maximum Product Subarray

Maximum Product Subarray

 

Find the contiguous subarray within an array (containing at least one number) which has the largest product.

For example, given the array [2,3,-2,4],
the contiguous subarray [2,3] has the largest product = 6.

这道题A了很久也没A出来，看了http://blog.csdn.net/salutlu/article/details/39560795做出来了

思路DP

max只可能来自三种情况

1.max * A[i]  // A[i] > 0

2.min * A[i]   //A[i] < 0

3.A[i]

当然min也只可能来自这三种情况

public class Solution {
    public int maxProduct(int[] A) {
        if(A.length == 0)
            return 0;
        if(1 == A.length)
            return A[0];
        int curMin = A[0];
        int curMax = A[0];
        int ret = A[0];
        
        for(int i = 1; i < A.length; i++){
            int temp = curMin * A[i];
            
            curMin = Math.min(A[i], Math.min(temp, curMax * A[i]));
            curMax = Math.max(A[i], Math.max(temp, curMax * A[i]));
            
            ret = ret > curMax ? ret:curMax;
        }
        return ret;
    }
}