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.

 

看《剑指offer》看到这道题，过来刷一下···

class Solution {
public:
    int maxSubArray(vector<int>& nums) {
        int cursum=0;
        int greatestsum=0x80000000;     //可以表示的最大的负数
        for(int i=0;i<nums.size();i++){
            if(cursum<=0)              //如果cursum为负，如果算上cursum会小于不算cursum开始的子数组的和，因此不需要前面的子数组，cursum扔掉
                cursum=nums[i];
            else cursum+=nums[i];
            if(cursum>greatestsum)
                greatestsum=cursum;
        }
        return greatestsum;
    }
};