[LeetCode]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.

发现leetcode又更新了一道题

Analysis:

similar like Maximum Subarray question

difference is the max value could be get from 3 situations

current maxValue * A[i]  if A[i]>0

current minValue * A[i]  if A[i]<0

A[i]  

We need to record current maxValue, current minValue and update them every time get the new product

Java

public int maxProduct2(int[] A) {
		if(A.length<=0) return 0;
		if(A.length==1) return A[0];
		int curMax = A[0];
		int curMin = A[0];
		int ans = 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]));
			ans = Math.max(ans, curMax);
		}
		return ans;
	}