LEETCODE--Maximum Subarray

Find the contiguous subarray within an array (containing at least one number) which has the largest sum.
For example, given the array [-2,1,-3,4,-1,2,1,-5,4],
the contiguous subarray [4,-1,2,1] has the largest sum = 6.
click to show more practice.
More practice:
If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.
方法一：

class Solution {public:    int maxSubArray(vector<int>& nums) {      //  int p = 0;        int q = 0;        int max = nums[0];        int val = nums[0];        while( q < nums.size() - 1 ){            q++;            if( val < 0 )                val = nums[q];            else                val += nums[q];            if( max < val )                max = val;        }        return max;    }};

方法二：

class Solution {public:    int maxSubArray(vector<int>& nums) {        int ls = nums[0];        int val = 0;        for(int i = 0; i < nums.size(); i++){            val += nums[i];            ls = max( val , ls );            val = max( val , 0 );        }        return ls;    }};