1、题目：
Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.
Example:
Input: [-2,1,-3,4,-1,2,1,-5,4], Output: 6 Explanation: [4,-1,2,1] has the largest sum = 6.
Follow up:
If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.
2、解答：这是选和不选的问题。若第i步的值加上num[i]小于num[i]则不选，若大于num[i]，则选。
3、代码：
C++代码
class Solution {
public:
int maxSubArray(vector<int>& nums) {
//vector<int> f(nums.size());
//f[0] = nums[0];
//for(int i=1;i<nums.size();i++){
// f[i] = max(f[i-1]+nums[i],nums[i]);
// }
//return *std::max_element(f.begin(),f.end());
int ans = nums[0];
int sum = nums[0];
for(int i=1;i<nums.size();i++){
sum = max(sum + nums[i],nums[i]);
if(sum > ans)
ans = sum;
}
return ans;
}
};
python代码
class Solution:
def maxSubArray(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
sum_num = nums[0]
ans = nums[0]
for i in range(1,len(nums)):
sum_num = max(sum_num+nums[i],nums[i])
if sum_num > ans:
ans = sum_num
return ans