152. Maximum Product Subarray

Problem

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.

Solution

维护一个到当前元素的前一个的最大值和最小值就好了，

开始有一个bug  : 应该用 tempCurMax 来临时储存下，否则计算 curMin时就算错了。

class Solution {
public:
    int maxProduct(vector<int>& nums) {
        const int N = nums.size();
        if(N == 0) return 0;
        
        int curMax = nums[0], curMin = nums[0];
        int rst = nums[0];
        for( int i = 1; i < N ; i++){
            int tempCurMax = curMax;
            curMax = max( max( nums[i], nums[i]*curMax), nums[i]*curMin);
            rst = max( rst, curMax);
            
            curMin = min( min( nums[i], nums[i]*tempCurMax),nums[i]*curMin );
        }
        return rst;
    }
};