leetcode 53 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.

动态规划思想：子数组是否包含当前元素，与前面的元素有关系。

代码

//可以返回0长度
int maxSubArray(vector<int>& nums) {
    int max_ending_here=0,max_so_far=0;
    for(int i=0;i<nums.size();i++){
        max_ending_here=max(0,max_ending_here+nums[i]);
        max_so_far=max(max_so_far,max_ending_here);
    }
    return max_so_far;
}

//不能返回0长度,至少一个元素
int maxSubArray(vector<int>& nums) {
    int max_ending_here=nums[0],max_so_far=nums[0];
    for(int i=1;i<nums.size();i++){
        max_ending_here=max(nums[i],max_ending_here+nums[i]);
        max_so_far=max(max_so_far,max_ending_here);
    }
    return max_so_far;
}