[leetcode]Maximum Product Subarray

class Solution {public:    //和最大子串和不同的是：需要同时记录最大的正数和最小的负数    int maxProduct(int A[], int n) {        if(n==0) return 0;        if(n==1) return A[0]; //这一句不能少，否则在就输出maxVal=0        int maxPosValEndsWithLast = 0;        int minNegValEndsWithLast = 0;        int maxVal=0;        int minVal=0;        for(int i=0;i<n;i++){            if(A[i]>0){                maxPosValEndsWithLast = max( maxPosValEndsWithLast*A[i], A[i]);                minNegValEndsWithLast = min( minNegValEndsWithLast*A[i], A[i]);            }else if(A[i]<0){                int temp = maxPosValEndsWithLast; //注意保存临时现场                maxPosValEndsWithLast = minNegValEndsWithLast*A[i];                minNegValEndsWithLast = min( temp*A[i], A[i]);            }else{//A[i]==0                maxPosValEndsWithLast = 0;                minNegValEndsWithLast = 0;            }            //update            maxVal = max(maxVal,maxPosValEndsWithLast);            minVal = min(minVal,minNegValEndsWithLast);        }        return maxVal;    }};