【有趣的面试算法题】之三 求最大子序列和/积问题，关注起点和终点

int maxSubSum(int* a, int n, int *seqStart=0, int *seqEnd=0)
{
    int maxSum = 0;
    int thisSum = 0;

    for( int i = 0, j = 0; j < n; j++ )
    {
        thisSum += a[ j ];

        if( thisSum > maxSum )
        {
            maxSum = thisSum;
            *seqStart = i;
            *seqEnd   = j;
        }
        else if( thisSum < 0 )
        {
            i = j + 1;
            thisSum = 0;
        }
    }

    return maxSum;
}

//找到长度为n的arr数组中最大的连续积
long long FindMax(int arr[], int n){
        if(n <= 0)return 0;
        long long result = arr[0]; //存储当前最大值
        long long tmp = 1;  //存储当前序列积
        
//从左往右扫描
        for(int i = 0; i < n; i++){
                tmp *= arr[i];
                if(tmp == 0){tmp = 1;continue;}
                if(tmp > result)result = tmp;
        }
     
//从右往左扫描
        tmp = 1;
        for(int i = n-1; i >= 0; i--){
                tmp *= arr[i];
                if(tmp == 0){tmp = 1;continue;}
                if(tmp > result)result = tmp;
        }
        return result;
}