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Given an integer array nums, find the contiguous subarray within an array (containing at least one number) which has the largest product.
Example 1:
Input: [2,3,-2,4]
Output: 6
Explanation: [2,3] has the largest product 6.
Example 2:
Input: [-2,0,-1] Output: 0 Explanation: The result cannot be 2, because [-2,-1] is not a subarray.
解题思路：key1:子序列意味着要在原数组中连续的序列，倘若放弃当前元素，即意味着之前所有元素均要放弃。
key2:与负数相乘，最大变最小，最小变最大。
class Solution {
public int maxProduct(int[] nums) {
int max = nums[0];
int imax = max;
int imin = max;
for(int i = 1;i < nums.length;i++) {
if(nums[i] < 0) {
//为负数,与最小数相乘变最大，与最大数相乘变最小。所以需要交换
int temp = imax;
imax = imin;
imin = temp;
}
imax = Math.max(nums[i],imax * nums[i]);//因为要连续，所以如果不选择当前元素，则表明需要跟以前的所有元素割舍
imin = Math.min(nums[i],imin * nums[i]);
max = Math.max(imax,max);
}
return max;
}
}